Try printing what you want to print to a file by ticking the Print to File box in the print dialogue box (I know it's there in word, dunno about other programs). Then assuming you printed to C:\print.prn, open a DOS box, and type

copy C:\print.prn LPT1:

and see what the printer does.

If it works, then the connection is fine, so something needs reinstalling, maybe printer drivers or Windows If it doesn't work, it's more likely to be a hardware problem, or possibly a BIOS setting on that port is set wrong.