installing libary

i have been unable to import library by using add library. get error message library already exist IT DOES NOT. can manually install but then they do not preform properly. this does not happen in 1.05 but this does not support the due. i have erased and RE installed nothing seems to work PLEASE HELP

It helps to explain the details - which library? Which version of the IDE? How did
you try manually installing it? What exactly went wrong?