well the other day my brakes started to feel weak so i checked to see if my pads were bad but they ended up still good, so i tryed to bleed the brake system and the brakes got it fimness back and felt fine but after a bit of driving the brakes started to feel weak and the peddle was almost hitting the floor again , so i turned the car off and pumped on the brakes and the brakes got firmer and firmer, then i turned the car on and the brakes just lost its firmness like that , need some advice before i go out and but something i dont need

 

brake rotors perhaps.... but i know very little about technical stuff.....

 

Look to see if your brake fluid is down. If it is your fluid is going somewhere. Check master cylinder, all calipers, brake lines, to see if any wetness is visible..
FYI, pads, rotors will not cause pedal to sink.

 

i checked the master cylinder and it looks dry, calipers and brake lines were dry also, if the master leaked where would it mostly leak from

 

it sounds like a seal in your master cylinder is leaking fluid past the piston. you can have it tested by a mechanic.

 

Sometimes you'll see fluid on firewall, inside. The master cylinder doesn't need to leak to be faulty. If seals go, pedal can drop down because there is no resistance inside cylinder assbly. I would check each caliper very closely before suspecting the master cylinder.
Has fluid in reservoir dropped?

 

no much dropped out of the reservoir but when i checked the master cylinder again i seen a wet stain on the brake booster where it connects to the master cylinder, would that cause the brake to go bad

 

Yes, once again, if the master cylinder is leaking, you will see it on the booster. If no power brakes, it will be on firewall.I forgot about brake booster.
If you thinks it's the master cylinder. you can remove it and see if any fluid is leaking out the back.