Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
First, let me say that Ive dealt with this issue many times. We can fix this. I can actually guide you through fixing this yourself without any tools or special programs other then what garmin provides for that unit. Best Buy is a store that sells products, and unfortunately the entry requirements for working at the geek squad are a bit low.. Hence they couldnt help you with what is a simple fix.
So, lets discuss the fix.. Lets try an initial repair and if this doesnt work, dont lose heart. It sometimes takes two or three different repairs to fix this issue, so whatever happens good or bad please send a response so I can assist you further or so we can close this issue out as resolved.
So lets start here.
This is how to reset the device ( and this is a video that shows the same procedure https://www.youtube.com/watch?v=aAOpw98cSpU )
The device will now reset. Follow the on-screen prompts and then place your device in an area with a clear view of the sky until it acquires satellites.
1Although the master reset will erase all saved favorites, any loaded custom points of interest will remain intact on the device.
Once that is complete, let me know if you can now search for cities normally or if the issue still exists. Thank you,
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.