this might help,
download the nokia care suite 5.xx
open the product support tool
if the tool can still detect your phone than you should be able to select it from a drop down menu in the upper left hand corner. now your product code shows up in the information box on the right
go to tools firmware download fill in the product code if it didn't auto detect download it
then go to programming and select recovery. Follow the instructions from there.
hope this works for you.
if the phone isn't detected my nokia care suite (which would suck) then this procedure would still work in which csae you just need to find the appropriate product code elsewhere.
if this is all too intimidating take it to a nokia care center and they can reflash the phone within 15 minutes.
Good luck!