Hydraulic brakes not working
They need to be bled. Nothing else for it. To do it yourself, you need a bleed kit and new fluid for whatever brake system you have, along with some other miscellaneous tools. It's considered a relatively advanced job as bikes go.

If by "very squeaky" you mean the loud howl of an oil-contaminated brake pad, you should just get new pads, and degrease the rotor thoroughly with something that doesn't leave residue.