USB mass storage no longer found??

Hi all,
Me again. So recently my desktop computer had a monitor stayong. Asleep and not waking up problem. So got that fixed yayyy!   so now. After that problem. I'm having an USB storage not found on my phone. When I connect my phone to my computer all it shows is my debugging and charging. Before my desktop computer problem it was working fine now. It doesn't I reinstalled my drivers nothing worked. I need it back. I would like to use pdanet again and not carry my old heavy computer (not as old as you think) all the way to another room and hook it up to a different internet. Thanks. Oh I should probably mention that it is a windos xp. Will anyone explain why this is happening? And how to fix it? Oh btw I'm on my smartphone. Wish my Toshiba laptop was working. Oy. Problems after another.