Compaq Presario CQ50-225LA Power Problem It is Not turn on What Could be the Cau

I take it you have it plugged in, correct? I had a compaq laptop a few years back where the internal psu took a crap, which based on your description, could be the issue. If this is the case, check your power cord going to it, i.e. does it have power and is the little light on the box turning on? If so, it is probably the psu, which depending on whether or not it is under warranty, I'd send it in to be fixed. If not, it may not be worth the repair cost to bring it to a computer repair shop.