If I am typing on the keyboard, it happens that some my letters still will be missing in the text, although I tap on them. Is that problem solvable.. ?

You're either not typing as accurately as you think, or your keyboard needs cleaning or repair -- if it's always the same key[s], or if you tap slowly and carefully on a particular key and it still doesn't register reliably, then it might be a keyboard issue.

Due to falling dust, dirt, hairs and something like that, the keyboard does not work properly, so first of all clean your keyboard from all four sides. It is often seen that even when the keyboard gets jammed, the keyboard appears to have problems while typing some keys.

When the keys on a keyboard don't work, it's usually due to mechanical failure. If this is the case, the keyboard needs to be replaced. However, sometimes non-functioning keys can be fixed. ... We have a separate page for troubleshooting keyboards that have no working keys.