external keyboard not workiing

when i purchased the ipad, i included a cover keyboard. the cover keyboard worked just fine until recently. symptions included; space bar not working, switching between open apps no working CMD-tab, caps lock not working, and onscreen keyboard popping up even when i was using the external keyboard. this had not happened before.

i fixed most of the problems by disabling the full keyboard access, but the problem of the onscreen keyboard persists. also, i solved the problem of the capslock but now the shift key doesn't work. i cannot, for example, capitalize the i in i.

why did all these malfuntions suddently start occurring/