How to reinstall os on coby 7" tablet? - Coby Kyros MID80244G Tablet

I don't know which model coby you have but - here is the coby kyros procedure

Can you try to do a factory reset by following the below steps and see if that helps you out:

1. First of all you need to turn OFF the device
2. After that just make sure its turned OFF
3. Now, you have to press and hold simultaneously POWER, BACK (return) and HOME buttons
4. Afterwards when the device turns on with COBY logo, keep pressing the above keys
5. After that the display asks to press the keys, after about 10 to 15 seconds, again within 5 secs to factory reset the device.
6. Now you just have to leave the power button now while still pressing HOME and BACK keys
7. If everything is done properly then factory reset will be started.

Usually on an android device access settings : sd card and storage : select erase all or restore or factory reset and device will be factory restored . If the OS is completely gone you may have to access an image from te Coby website and install from a laptop by cable .