Unless you have the appropriate knowledge and equipment there is a limit to the repairs that can be undertaken safely. However, there are a few simple things that can be checked before calling a specialist under floor heating repairer.
First of all start with the basics. Is there a hot water supply available? We have known cases where, on large properties, one boiler is supplying the under floor heating while another supplies the domestic hot water. Circulating pumps for under floor heating, or any heating system, can seize up if left unused all summer. Sometimes these can be freed by a sharp tap to the pump, or by removing an end cap on the pump and turning a slotted shaft. Once again we must stress that you should only do this if you feel competent to do so. Under floor heating pumps are usually not of all summer, depending on the type of control system used, but we have known them seize in this way.