Hi, Blown fuse in my old style house fuse box but i changed it when power was still on!!!?

I doubt that you've damaged the fuse-box. Time to test that fuse. It may have opened when you tried to insert it. (Whatever caused the old one to open may still be there.) With a test lamp or meter: First test from the 'line' side of the fuse holder to ground. You should get a positive indication. Then test from the 'line' to the 'load' sides of the fuse holder. - A positive indication means that: *there is load, or a short on the line, and *that the fuse is 'open'. Note: The sparks when you tried to insert the new fuse 'power on', indicate that either there was a load on the circuit, or that the circuit is 'shorted'. If the later is the case, it's time for a pro.  more