how can i fix my heating system?

in an attempt to take the radiator off the wall we broke the opposite end of the thermostat valve,we turned the water off at the stop cock but the radiator had leaked all of the water out by the morning, we to cut the pipe and put a new valve on, now we have turned the water back on bled the radiators but nothing is working no heating or hot water and the system is making a high pitched squealing noise.We were then told to put a hose pipe to the lowest radiator and allow the water to flow into a bucket ,this also did not work. the make of my boiler is a Baxi Solo2 rs
I'd be gratefull for any advice you can give