i'm lost, i don't know where the machine room key is,how to blow up the locker ,get this valve handle, and get this gas mask.

you can't blow up the locker, this comes later in chris's scenario. help him out by getting the detonator and placing it on the explosives. when chris comes here in his scenario it is on fire (when you place the detonator it gives you a message it is heat sensitive) which has blown the lock. he must have the fire extinguisher here to reach whatever is in the locker (ammo i presume, or maybe a weapon - doubtful on the weapon as he will also find a magnum in the room). to get the gas mask you need to first go into the bow room and find the shipping sticker. now assuming you have turned the power on, go back to the sorter machine room and turn it on. when it brings the box marked bow on it, place the sticker on the box and turn the sorter on again. go back to the bow room and the box is busted and leaking, allowing you to get the precious gas mask. As for the machine room key, not sure, let me peruse my notes and get back to you.

if you have already found the valve handle, take it back to room with the zombie stuck in the cage, use the machine shop in the back to turn the square valve to the octa valve. will get back to you on where the valve is in the first place if you have not found it yet. i am assuming you are still playing claire scenario so if this is wrong assumption please let me know. you can't use the valve until steve crashes the machine into the pipe anyway. good luck

have to take back part of a previous message. the fire does not blow the lock. i am just guessing but i think you have to have chris use the lighter to set off the explosive (get it: heat sensitive, fire from lighter). sorry i can't verify this for you right away but i am playing chris's scenario without the lighter (i made the goof of not saving raval right away and when i went back to save him, killed the worm, etc. he was already dead and didn't give me the lighter. bummer, no pair of sub machine guns, no (hopefully) locker in weapons room, no whatever else you need the lighter for. i will soon be replaying and getting everything right this time

still have to verify but i'm pretty sure after you get the gas mask, go back into the room with the gas, and go out the door on the other side you get the valve handle (you can save this hastle by going into the other room first - at least i think you can go here first - to get the valve handle, then check the levers in the other room to let steve crash the digger, gas attack, etc. - course you still have to have the gas mask to get into the other room to shut off the gas but at least you could go ahead and make the octa handle on the way down.

OK OK IN ORDER THIS TIME
1) the machine room key can be found in the safe room on B2F (i.e. the room with the item box and save point). you must first turn on the power, then push on the book shelf in the back, take the butler's letter (file) and push the switch to open the secret room with nosferatu underneath. check in a corner to get the plant pot, check under the plant pot to find machine room key
2) locker is still suspect, but think you have to wait for chris and the lighter
3) to get the valve handle you must first have the gas mask (i think - still verifying)
4) to get the gas mask, first go into the BOW room and find the shipping sticker. now assuming you have turned the power on, go back to the sorter machine room and turn it on. when it brings the box marked BOW on it, place the sticker on the box and turn the sorter on again. go back to the BOW room and the box is busted and leaking, allowing you to get the precious gas mask. if steve has not already released the gas, go to the machine room, check the levers and steve catches up to you. he operates the levers to raise the giant digger, etc. and ends up breaking the pipe and letting the gas into the room. afterwards you are outside the machine room. go back into the room with the gas, and go out the door on the other side to get the square valve handle (you can save this hastle by going into the other room first - at least i think you can go here first - to get the valve handle, then check the levers in the other room to let steve crash the digger, gas attack, etc.). of course, now you have to go back to the room with the zombie trapped in a cage on B1F, go in the back and use the metal shop machine to get octa valve handle. now go all the way back to the mining room on B2F (note: be sure you will leave two empty slots and have some extra weapon like handgun and bullets or bow gun and arrows handy - don't overdo it either - and maybe a health item or two - one triple strength or two single or double strength). that's all i will say. for more check out
http://www.angelfire.com/games3/psonegames/ and follow the ps2 link to my re:cv walkthrough