I would let the restore complete. Hopefully, you made a backup so restore it and you will be ready to go.
Lets make an assessment
did you make a backup before trying to install the new rom?
are you using SPR?
Were you able to get back to the backup/restore selection? If so, my sense is the nandroid backup did not activate.
If you want to be safe restore the backup you made prior to starting. Highlight the backup/restore line press camera button. The highlight restore, press camera, select the backup you just made and press camera.
If not, then keep going with the install of the new rom.
I use the advanced nandroid so I'm not positive. My sense is that you should check the same that you checked when you made the backup.