I happen to be a K-x user myself, although I have not run into this problem personally.
The manual suggests turning off the camera, taking the batteries out and leaving them out overnight before putting them back in.
You may want to try a fresh set of batteries, just to make sure.
A similar problem was reported here:
https://www.pentaxforums.com/forums/58-troubleshooting-beginner-help/279489-c...l-menu-kx.html
In this case, it seems as though the owner may have had to take or send the camera elsewhere for diagnosis and possible repair.
As a side note, I suggested in the other case trying a firmware update/reinstallation. However, I do not know that it would make any sense to try to do this when you are unable to use the screen or the control buttons. So I might personally try a firmware update in that situation if nothing basic helped and I would otherwise be stuck sending it in for diagnosis and possible repair anyway, but I would not (any longer) recommend that anyone else try to do this.
Best wishes,