halogens stoppped working for 3 days, now it works!

It sounds as though the transformer is overloaded or faulty: I'm assuming there's only one, else it would be unlikely that all the lights would stop working at the same time. You say you have a Varilight switch: I'm assuming this is a dimmer? There are some combinations of dimmers, transformers and lamp types that do not work in combination. I've seen a dimmer work ok for 3 years before giving up the ghost. Upon replacement, the transformer was found to be dead, which then destroyed the new dimmer. So it may not be a simple matter of determining the appropriate rating for a new/replacement transformer and then getting hold of one. Get a competent electrician in (check his registration details) to take a look over the kitchen lights and sort it out for you.

I agree with all above but another issue could be transformer size it may be too small for lamp load,( try smaller lamp size ie from 50w to 35w or it may be overheating and the thermal cutout is operating maybe too much insulation around transformer not allowing enough heat dissipation