Not being able to type on MAC OS X Launchpad can be caused by several issues. Installation of new software, accidentally pressing a combination of keys or lack of memory in your MAC.
Here’s a quick fix:
1. Close all running applications by using force quit.
2. Log out your user.
3. Log back in, then try again.
4. If this fails, try opening Launchpad and press tab multiple times.
Watch video instructions: