I got a new boiler installed and thermostats put on all my rads etc a couple of months ago, last night i bledd 2 rads as they were cold at top and hot at bottom, since i bleed the rads my bioler is now showing no pressure on the gauge, although i the hot water doesnt seem to have lost any pressure and all the rads work etc, i cant get hold of the plumber who installed it, so until he is back is there anything obvious i can do to sort it?

cheers for any help