Initiating legal action for termination without any reason

Termination without Notice Period

I'm working in a company for over 7 months, and my probation period is finished. I have an unlimited contract.

In my offer letter and also in my contract, there is a 3 months notice period but they suddenly terminated me without any reason.

Should I get 3 months salary if go for legal action?

Could you please explain the procedure to move legally?

And how much time will it take for the legal action and get the benefits?