samsung gt i9000 does not start I flashed my Samsung Galaxy S with 4.1.1 through Odin. But I didn't like it, so I wanted to restore it to Android 2.3 -- and and while restoring it, my computer suddenly restarted and my mobile phone turned off.

Now the problem is that when I try to open my mobile it doesn't respond.the screen gives me nothing. When I try to start it in download or recovery mode it does the same.

I tried to connect it to my PC but nothing happened. When I charge it, it gives me nothing.

I replaced the battery and it did the same.I connected the jig(301k), nothing.

Is there anything I can do to revive my phone?
It sounds like you have hard-bricked your phone. The only thing you can do to get it back is send it in to get it jtagged, or jtag it yourself. The jtagging process is quite complex and unless you have a lot of experience in hardware hacking, you probably should just send it in to have someone else do it right.
I had a similar situation to the one you're in:

Is there a way to restore my Samsung Galaxy S3 (SCH-i747)?

Which ultimately led to:

How risky is it to return a rooted android device under &#39;warranty&#39;

I returned my phone to AT&amp;T under warranty and they just send me a new one. I did a lot of research on AT&amp;T and Samsung to see their policies on returned phones. Basically after searching the internet for a couple of days I had concluded that the general consensus is this:

Should you return a bricked phone that you were trying to root? No, it is a breach of the warranty and the warranty is null and void
Will I get caught if I try to return a phone that I bricked while trying to root it? Highly unlikely.

If your device is not under warranty, then you have to send it in to get jtagged. In order for your phone to get jtagged, they have to open it up and do all sorts of stuff to it. If your warranty is still in effect, I would highly recommend going that route first.