My other guinea pig died yesterday and now the one i have left is very lonely. will she be ok?

It is likely that she will need a friend. If you have a local shelter, try and find another guinea pig the same age to pair them up. I do warn you though, female guinea pigs do fight more than male ones! I would consult the vet first. It may be that she adapts well to living alone depending on her age. Only time will tell. P.S sorry to hear about your Guinea pig. X