when i try to stop the brakes lock up no matter how hard or soft i press them on 1995 GMC Jimmy

i did not do any thing to them ,, i think i touched something under the hood

Asked by for the 1995 GMC Jimmy
Are there any warning lights on? ABS lights?
Do the front brakes lock up? The rear brakes? Both?
I'm trying to help you, but if you cant provide more information, I can't help you.
any help........... this site is worthless