Mouse buttons - left and right doing same thing

Hi folks

My right mouse button used to give me a small number of useful options (copy, paste, etc) but for reasons unknown it's now performing the same function as the left mouse buttons.

Anyone know how I an revert to the previous setting? I've got Windows XP.

Many thanks in advance.

you can go into control panel
-mouse
-settings
-left/right button

control panel - mouse. change the button settings from there.

Sorted.

Many thanks to you both.