Well,

If it's not a workspace, not a profile and cadMEP is loaded, then something has to be broken and not just misconfigured. You can try the repair, but your CAD gremlins may very well be stronger than a repair can fix. So, if this repair process doesn't fix it, then you will have to technically reinstall AutoCAD. Which can also be done through the repair dialog, but it may need a complete uninstall -> reinstall from scratch if it persists.

FYI, The Fabrication tool bar is 100% dynamically created; it even reloads while CleanScreen is actived. It isn't backed by any traditional CUI elements and thus should be there unless something is pretty broken. 

To do a repair:

Open up the programs and features part of Windows, find AutoCAD, right click and select Uninstall/Change in the context menu; just follow the dialog from there.