Only if you have a backup stored somewhere. Are you sure that you deleted it, or did LR lose track of it? Try searching your computer for files ending in a .LRCAT extension. If you find one, double-clicking on it will bring up LR using that catalogue.
To extend on Hal .. if you have used LR's backup function you can restore to the latest version of it. You'll loose all your work from the time the backup has run up to now.
Check the "trash" or "recycle bin" to see if you can do an undelete.
Otherwise, restoring the catalog from backup is your best bet.