I am not able to open any file with fin...

Try opening system preferences and looking at the settings for mousepad. If that all appears to be set correctly try resetting the power manager. 1.Shut down the laptop 2.Remove the battery and disconnect from the power 3.Push the start button and wait 5 seconds. 4.Reinstall the battery and reconnect the AC power. 5.Reboot the macbook you should be able to confirm that the power manager has reset when the light on the magsafe adapter turns off briefly as the power manager resets.
If that fails to correct the problem consider replacing the trackpad.
Hope that helps