I assume you are talking about the sockets in the dash? If so, there is no simple fix as pointed out by others. It’s possible the converter swapped them to work off the LB for some reason or the fuse has blown while they were doing the work. Fuse is either under the passenger seat or in the fuse box under the gear lever (far left bank of fuses, half way down, 15a fuse all on its own) depending on age, options etc.
The simplest fix would be to pull out the little cubby hole with the 12v socket by the gear lever - it just pulls out (it’s stiff and may need a little persuasion with a trim tool). You could then disconnect the plug to the 12v socket and replace the leads to connect the positive into a spare fuse slot by the gear lever and the negative to one of the screws just above the fuse bank. The positive could be ignition switched by using the upper central row of fuses and either a single or double breakout fuse. Examples below. Not a complex fix but probably a bit awkward if you are travelling and haven’t got tools!
Pic shows double breakout fuse in ignition switched central row (middle circle). Negative connection is screw (right circle) and location of possible 12v socket fuse (left circle).
Example of single breakout fuse:
This can be connected into many of the empty fuse slots instead of the double shown above. You need to have a close look at the empty slot and ensure it has the metal connection visible on the right hand side of the slot (this provides the power). This breakout fuse then fits with the wire coming out to the left.
Good luck.
