Monitor is not detected anymore

[Heleen]

Hi,

I have a MacBook Air and a portable external monitor, (AOC I1659FWUX) It is connected through a usb 3 bus.

It used to work fine but I can not seem to get it working anymore.
If I want to detect another display apart from the built in one it is just not recognised..

The monitor does still show up in the system information (see attachments also Display Link information report) and it is also powered because when connecting through the USB the AOC logo is ,shortly, visible. Afterwards though the screen goes black. It still works fine on a pc.. I tried everything from removing and installing DisplayLink to installing the OS anew (Mojave 10.14.6) , rebooting, NVRAM etc,,

I am not sure but I think the problem occurred after installing Mackeeper..... (I removed it !!!!) however they do not think this is possible.... but it probably did damage some files here?? Can I still repair? Please heLP Thank you
Can anybody help me out here? Thank you!