Switch it off and don't use it!
Did you format the entire HDD or just a partition? It might be that the stuff you need is on a separate partition. Our company laptops have two partitions, with the "Documents and Settings" on D: which allows for a machine to be rebuilt without the need to backup user files.
Failing this, you may need to send the disk away or buy some recovery software. Googling "harddisk recovery after format" returns numerous links. I'm afraid I cannot recommend any as I have not been in your situation.
Good luck.