How Can i Delete files and copy files from pc?

I cannot Delete Files ? and when i m trying to copy anyfile i can't copy .

and Recieve the following problems.

Access is denied

There has been a sharing violation.

Cannot delete file or folder The file name you specified is not valid or too long. Specify a different file name.

The source or destination file may be in use.

The file is in use by another program or user.

Error Deleting File or Folder

Make sure the disk is not full or write-protected and that the file is not currently in use.