What were you doing when you noticed the message about shortage of space on the SD card? To my knowledge the nüvi 200 won't display any such message. Your computer possibly, depending on what you were trying to achieve. Whatever files you deleted from the SD card, the operation of the nüvi should not be affected.

The below screenshots are taken from a nüvi 200W, but apart from the window size should be identical to the ones you can see on a nüvi 200.

7zDy02k

If you see this message, you may ignore it. Has to do with the internal memory of the nüvi. Your unit will continue to work fine. If the message disturbs you, reset the nüvi to factory default and the message won't be shown anymore. Backup personal settings first (e.g. with Garmin Express) as you will lose those.

Quote Originally Posted by Neil View Post
<...> but it should still start and work even without such files.
tySodhc

If there's no longer any map available, this could be a reason the unit stays on the above screen (notice the absence of an OK button). It would therefore be interesting if the OP could clarify what is meant by:

Quote Originally Posted by Emerald View Post
<...> now my unit refuses to work.
What exactly does the unit do when switched on and what does it not do (anymore) at which point?