Hello Eyad,
According to the screen shot, your ArcGIS Server has only the "Image Server" license role. You will need the "ArcGIS GIS Server" license role for the services.
Go to my.esri.com > my organization > licensing > view authorization > ArcGIS GIS Server > version 10.6-10.6.1 > details > Copy the ECP number.
Go to your ArcGIS Server machine > launch "software authorization for ArcGIS Server" from the windows menu >
1) "I have installed my software and need to authorize it"
2) If you have internet on the machine select "Authorize with Esri now using the Internet"
3) Fill out your and your organization's information in the next two windows
4) Enter the GIS Server license ECPcode in the blank space for "ArcGIS Server"
5) Finish authorization.
Check in https://arcgisservermanager > site > software authorization > if the GIS Server role is now showing up and all your services are visible.
If not, please restart the ArcGIS Server service from services.msc > ArcGIS Server > restart.