Go inside your PC and check you have everything connected properly and its not had any cables nocked out, you might want to try resetting the CMOS when you stick the old memory back in.
Oh and dude maybe you should post your complete problem in something readable you know bullet points would be good something along those lines, do what dsnette said to get the data off anyway and anything else you need that you cant lose, stick it in a freinds or family members PC copy everything you need to their hard drive then burn the data to a disk or onto a USB pen. After that to finish your project there is always the library or the old fashioned pen and paper. You really have to be careful when working on important stuff i copy my entire Uni work folder onto my usb pen regularly so im never without my work or PDFs i need.
Edited by warriorscot, 29 November 2005 - 01:49 PM.