How to fix a phone line with no dial tone?
There is a wiring fault somewhere between the phone and the telephone exchange, or a fault in the telephone exchange itself. If you have more than one telephone socket, see if any others work - if they do, it's a fault in the wiring in the house. If not, it is an external fault. That is usually the responsibility of the phone company; you need to report the fault to them. If the fault is in the house, who is responsible depends where in the world you are and the telephone company rules. In some places only the company is allowed to work on telephone wiring, no matter where; in others, all extra wiring beyond the first socket is the responsibility of the homeowner.