Help Mistake , upon recovery cannot boot anymore

[tanauser]

Hello
I have tried to explain all in the title
I have Samsung S3 i900 , I was in the recovery mod when I did this mistake
now I cannot boot and the phone is not anymore recognized by laptop windows 7
Is there a way to reinstall ( Odin cannot see the Smartphone even reinstalling the drivers) ?
Shall I resign myshelf ?
thanks in advance

 

[SavageRobot]

What mistake did you make? Are you saying you are actually in recovery? Did you make a nandroid backup? If so restore. If not still have the ROM on SD? If so reflash? If not can you get into flashmode (can't remember what it is on Samsung but on Sony it is shut phone down completely, hold vol- and connect USB). Odin should find it that way?
What happens when you turn the phone on? Nothing, bootloop, long booting process or recovery?