Hi I have an outside toilet which it part of my outside sheds. Quite a few years ago the toilet did used to work but now it just doesn’t get any water supply and I don’t know why.
Is there a stop tap on the pipe work if so see if it's on and if so most likely be the toilet system has stopped working
the mechanism of the cistern is blocked it has to be replaced
Sometimes the float valves can calcify & stick in hard water areas, with being out side & not in frequent use this is quite common. the valve may just need attention or a replacement , a competent plumber will be able to diagnose the issue via a maintenance visit ,
hope this helps , regards Ric
Plan design & build Ltd
May be frost damage, or just a stuck ball valve.