I cannot use the mouse /touch pad at all.it happened suddenly?

your touch pad had to be replaced (physically mean)

Did it work for you before? what has happened since then?some laptops have a way to disable the touch pad so you won't accidentally move the cursor while typing. It may be a switch on the computer itself, or a LED in the corner of the touch pad, or it may be one of the Function keys (does any of them have a symbol of a mouse with a circle and one diagonal line indicating "no mouse") If so, push the fn key plus which ever function key has that symbol beside it.Some laptops automatically disable the touch pad if a USB mouse is plugged in.If none of these is the problem, you may not have a touch pad driver installed. Get a USB mouse to plus in until you get the driver installed. Go to the web page for the manufacturer for the laptop. Search for your model in the support section, and look for drivers. Download the appropriate driver for your touch pad and your version of Windows, and install it.Buying a USB mouse or a wireless mouse may be a valid solution no matter what the problem is if you like a real mouse.

This has happened to me and it took me hours to figure it out. I hope yours is the same problem...
Make sure you dont have your touch pad set to off. On my ASUS It is F9 on my keyboard. the key shows an icon of the touch pad with a slash (/) through it. If you do not see this on your keyboard try looking in control panel and see if there is a setting in there. Good Luck. Please let me know if this worked.
Geraldine

You are probably using a laptop with a touchpad. What is happening is that your thumbs are touching the touch-pad as you type and the cursor is jumping around. Solution: disable your touch pad. You can go to Start > Control Panel > Mouse > Touch Pad > Disable

Another solution is to go to the Dell website > Support and Drivers > download and install the Synaptics Pointing Device driver and disable your touch pad using the options in this new driver.

seems you need to replace the touch pad, if you have warranty on it return it and have them replace the touch pad

try it with toggle keys it may be work

check driver in device manager update
in control panel check the settings for mouse.
clean the mouse pad
let me know

restart the machine after unpluging the usb mouse and then press fn+f8 simutaneously twice i hope it should work.

Hold down the function key and press F9. That enables/disables the touch pad. The function key is the one with the letters 'Fn' on it. If that doesn't work, let me know and I well explain the long answer.
Good luck, and let me know how you made out. and please rate my answer.

Hello
Most probably because your 'Touch Pad Mouse' is touched by your palm (hand or something) while you are typing. Avoid contact with the mouse touch pad while typing.
Option 2:
If you have a centre moveable mouse on your laptop, start using it and disable the 'Touch pad mouse'
Best of luck!