Why do tools become disabled?

[Anonymous]

I am very new with Revit.

Why do Revit tools under the Architecture tab become grey and disabled?  And how can I re-enable them?

Thank you for your help.

[L.Maas]

From your screenshot I see that a command (floor) is already/still active.

This means that during this command execution, many other commands are not allowed and therefore greyed out

[Anonymous]

I do not understand your answer.

How do I get out of the command?

[L.Maas]

Go to the tab of the active command. Then confirm V or cancel X to complete command.