Chosen Solution
when i type any letter it is deleted
Your backspace key or the contact underneath is likely stuck or dirty. I would look up your specific computer for recommendations for your keyboard but most times a key can be carefully removed from the keyboard by prying with a spudger and then cleaned. I would use a quetip and a small amount of isopropyl alcohol to clean the underside of the key, the plastic/metal brackets that hold the key in place, and the contact if possible.
