I went to plug in my camera to transfer pics & accidentally put wrong end into USB port ( didn;t fit- but touched) & computer immediately shut off & won;t come back on- tried unlugging...nothing- help
Sounds like you have at least fried your power supply (If may just be a fuse inside the casing, but these are difficult to get at and often soldered in. So it's a take it down to a shop job).
You may also have damaged the main board. You could try another power supply and see if your computer starts up.