LR 4/5 won't open on computer

I have two versions of LR (v4 and v5) both of which I paid for.  I haven't used the program in a long time (I'm not a professional photographer).  But I want to use it to clean up some headshots that were taken of me.  The program won't open on my computer.  I called Adobe and they said I should reinstall the disc.  It was a download, not a disc.  I've paid for this program already plus the upgrade to newer version.  Do I have any recourse or do I need to pay for a whole year subscription?  Again, I just need basic editing tools to clean up blemishes... nothing more.  Any suggestions?  Thanks!