I think you've re-flashed the FTDI device in your USB-Blaster. This is different to erasing the CPLD in there, the code for which is not available.
You should be able to fix that by using FTDI's FT_PROG utility -
see here (
http://www.ftdichip.com/support/utilities.htm#ft_prog). However, you'll need a file to reprogram into the FTDI device. So, you will probably need some kind sole on the forum to read it out of their USB-Blaster and post it here for you to use - this is sounding strangely familiar...
What version of USB-Blaster have you got?
Cheers,
Alex
PS. If I remember later I will do this, just for you.
PPS. Just
found this post too (
https://www.alteraforum.com/forum/showthread.php?t=43986). Might already have the file you need...