I just bought a new HP Tablet PC - tx 2627. After 4 days of use the keyboard stopped working. None of the keys work. The mouse pad and touch screen work. I am in Afghanistan where there is no HP service centre. Can someone help please?

Try another known working keyboard or buy a brand new one

Check the on/off button on the keyboard and check with different
Usb port.
If you can arrange the another keyboard then, check it whether it is working or not or you can set BIOS default settings.

As you just purchased it, do you have the option of returning it?