I cleaned my desktop computer ( that is connected to my router with a cable) with CCLEANER RESULT: INTERNET connection lost, with the message in my task bar saying that the cable is disconnected. It is not. Any suggestions please?
Try running System Restore back to a point when it was working properly. Ccleaner shouldn't normally affect your ethernet connection, unless you've used its registry cleaning option and that's messed things up.
When cleaning the registry, Ccleaner gives you the option to backup the relevant keys before making alterations. Did you let it create this (.reg) backup file? If so, double click it to restore the original registry settings.
If "System Restore" back to before the problem arose doesn't fix it, go into Device Manager and Uninstall the network adapter. Then reboot so that Windows "finds new hardware" and reinstalls the adapter. See if that works.