please help

Hi i have a Compaq desktop SG3_250UK Im trying to do a factory reset....it says i dont have it on my partition...i do have a HP_WSD.dat file.on my d drive. Its a image and the file is saved as a nero file so im wondering if the file its saved as is interfering in it...im hoping this is what i need to reset...but nero..which i used for copying muaic onto disc is the default program for the file...anyway i tried to do a repair disc but it wouldnt i got an error 0xc000000f so i then had to download exchange 2003 which wont run because it needs over 500gb which i dont have....im really lost as ive ran out of warrenty and im unsure what my options are without a hefty bill. Pleeeeeaae someone help me i beg( im actually on my knees) haha

Thank u in advance

Amylee xxx