Which programs were you using? I assume it was a good one. If so, check if it has a rollback option or a restore option that it has backed up before doing the fix.
Also, on a side note*... How long does memtest usually take to run? I did it once on my laptop and it took over 14 hours and it still kept on going.. After this, I left and a couple hours or so later came back.. my laptop was off..