Lost key to TV cabinet with barrel lock how can you open it any advice gratefully received?

Answer 1

It depends on the latching mechanism of the lock.
Did you ever look at the back part of the lock?

If it's a spring loaded wedge shaped latch, like you have on a door, you can slip a knife in above or below it and slip the latch out of the striker plate.
There'd be a notch in the other door with metal plate with a square hole in it.

If it's got a metal strip that turns with the lock when you turn the key and catches in a hook or butts a metal plate on the other door, you're going to have to drill it out.
It's not very hard to do, all you need is a drill and a 1/4" bit. Drill out the spot where the key goes in. This will drill out the tumblers.
Once you're done you can open the lock with the turn of a screw driver.
The lock is cheap enough and you can pick up a replacement at most hardware stores.

Picking locks is an art, but there's one thing you can try.
If it's a conventional lock, and the key looks like most padlock and tool box keys, stick a hair pin or a very skinny hex key into the lock all the way to the back and then angle it so that the end you're holding is headed down. Some inexpensive locks have a release that will allow you to pull the lock cylinder out and you can then open the latch with a screw driver when you've got it out.

Good luck!