Kodi box is locked

Hi all, got a wicked problem with my kodi box, left it in superb running shape and asked my neughbours kid to look after the house while I went to clean up cottage, showed him the box and told him how to use it, kid said he knows how and not to worry.
Today I come back and the box is locked/frozen, upon starting form original menu an icon came on with a “Master Use” icon and then asked for a lock code, asked the kid what he did and he said not to worry, just type my name and all will be fine, he supposedly knows this stuff, so I typed my name and the blue kodi menu comes up, but, I only have “System” and “Pictures”…… no Video, no Programs, no Weather, the kid said he installed Quasar for better protection, but now this genius knows no method of unlocking my machine.
I went into System and disabled and deleted anything that said Quasar from tepositories, but still no Video skin, or Program skin.
Gave it hard shutdowns by unplugging it and still frozen, ……… I can go in and out of System, but I can’t get thet Program skin on to purge and restart.
Does anyone know of a quick fix for this, otherwise I might have to go out and buy another box………..it will be a crying shame for I took painstaking care of installing three wicked zip files and customised it with my tastes, and I might have to go through this all over again……… Jim Charinos