What type of computer? Have you tried using a USB keyboard to see if the problem is reproduced? Did any liquid spill inside, to your knowledge? Give a bit more information so that we can try to narrow things down.
Maybe try this:
In System Preferences, check International and make sure that English is at the top of the list under the Languages tab and that the Region is correct under the Formats tab.
Also make sure that nothing foreign to your language is ticked in the list under the Input Menu tab.
If anything needed to be changed in the International preference, restart your MacBook for it to take effect.
If nothing changes, do you have another USB keyboard you can plug into your MacBook to test the 7,u,j and m keys - just to see if it can't read those same keys on another keyboard?
If none of this leads anywhere, take it into an Apple Service Centre.
I pulled this from another site, ergo the reference to MacBook. I am making a presumption, but should work with a PC, as well. Let us know the results.