Can no longer ftp plugins

I solved this problem by clearing browser cache and rebooting my system

Out of the blue I can no longer upload plugins or access my ftp server via web browser. I am using a lamp server on localhost. I’ve been able to load plugins via ftp until this morning.

This: Failed to connect to FTP Server localhost:21

And this: To perform the requested action, WordPress needs to access your web server. Please enter your FTP credentials to proceed. If you do not remember your credentials, you should contact your web host.

I am using the same credentials as previous plugin uploads.