Short for Where. Many Spelling Reformers opt for omitting silent letters or ending vowels that aren't pronounced.
Wher hav u been? Wel, I'v been in a hurry & very bizzy (busy), working, washing clothes, duing homwork, calling my frends, text-messeging others & chatting onlyn'. Lyk I don't hav that much tym so I typ' lyk that & fast.