Go to Data -> Calculate -> Recalculate. The hotkey for this is F9 on my machine.
If that does not work, start with a new spreadsheet. Enter =RAND() and see if recalculating changes the value.
Go to Data -> Calculate -> Recalculate. The hotkey for this is F9 on my machine.
If that does not work, start with a new spreadsheet. Enter =RAND() and see if recalculating changes the value.