My phone isnt turning on

I charged my phone to 95%, plugged it out and immediately, the screen turned black and I couldnt turn it back on no matter what I did. I tied remving the battery, removing the sim card, leaving it to charge (also when I tried to plug it in nothing happened) for 48hrs, rebooting it and pretty much everything you can think of. I asked my friend and she told me that trying to repair it would probably cost more than buying a new phone. I ve also been experiencing battery problems for a few months now, it would get to around 50%, turn off and when I turned it back on it would be on 1%. can someone please give me some advice.