Try reinstalling the keyboard driver. Go to Device Manager, double click Keyboards, right click the internal keyboard and click Uninstall. Restart computer and the driver will be automatically reinstalled.
If you post here again, please include your COMPLETE model info as in my examples below.
C.B. Toshiba Sat. L675D-S7016 Win 8 PRO 64 Bit---Toshiba Sat. L775D-S7132 Win 7 PRO SP3 64 Bit which also has Virtual Machine with Win XP SP3---Toshiba Sat. L305-S5921 Win Vista SP2 32 Bit