Why My phone switches on and remains in switching mode permanently

hi, since yesterday 16th February 2015, while calling someone my phone stayed in call mode without connecting to the other end. tried switching it off in vain. so I removed the battery to try restarting it, it switched on and could not go further than that- the switch on lights permanently ON.

I've tried it severally in vain, what might have happened here?

while charging it shows the charging indicator on screen but when switching ON nothing happens, assist and give me a solution, the phone is carrying a lot of my data I'd like to save if it cannot be revived