Why is my Apple Wireless Keyboard connected and paired, but I can't type anything?

Hey,

I’ve been using Apple Wireless Keyboard (A1314) for a year now. Yesterday it stopped working. I can see it’s connected and paired, but I can't type. I tried unparing and pairing it again and sometimes it helps - I have no idea why, but once in ten attempts it works. When it works, though, some strange happen - like my Mac increases it’s volume level like I hit F12 on the keyboard.

When I go to Bluetooth menu battery level is hardly ever shown up. Also, when my keyboard is connected it takes a few seconds to open forementioned bluetooth menu.

So, it there change I will be able to repair it? It’s not like it costs $5. :c