I accidentally restored a SQL Server 2008 database with a wrong backup. Is there any way to undo this and restore to previous version?
Unfortunately no. The only solution is to do another restore with the proper backup file(s).
Unless you can restore from the correct backup, no.
No. You've replaced what's there with your restore. You would have to treat this the same as someone dropping your database - go to the most recent full database backup you have and then restore all subsequent log backups.
Sorry... you probably have that sick feeling right now. I feel bad for you.