The function of my laptop's keyboard buttons has changed

So whenever I try to use the keyboard some of the buttons would open a browser. An example would be pressing ENTER.
If I press F my pad gets locked and I can no longer use it.
If I press Tab my brightness increases.
If I press F1 the calculator opens.

It's as if the function keys at the top of the keyboard are now part of the main keyboard. Some letters type three letters at a time.

This is a HP Pavilion laptop.