Brake Problems

I searched and I’m thinking I have a bad master cylinder but I’d like a second opinion. Today I went to drive my car and my brakes are almost non existant. They work but are on the verge of locking up. The pedal goes almost all the way to the floor and then finally works but just barely and anything over a touch of pressure they lock up.

I tried to stop for a stop light and my left rear locked and no others seemed to work. Brakes were working fine yesterday. I haven’t had a chance to look into anything yet I will in the morning but I have no brake fluid leaking that i’ve seen on the ground.

Just checked and I have no brake fluid in my reservoir.

Does this mean I probably need a new master cylinder?

If you were driving with basically no fluid in the reservoir then you most likely have air in the system now. On top of that, the fluid had to get out from somewhere so you need to check for leaks.