The image below is from Bikeforums. Basically, Shimano shifters can fray the cables like this, because there's a really tight bend in the cable which stresses it. It's generally recommended to replace your cables regularly. A mechanic should be able to disconnect the front derailleur and pull the cable out partially to check its status. If the cable is broken entirely, that's not great, as it can be some work to fish it out.
I mention this because while we don't know exactly what's happening, this could explain failure to shift. This is why the comments are asking you for further information and to further diagnose the issue.
If it comes to that, you could use any 11s Shimano shifter, and the 105 shifters (R7020) are a bit cheaper and functionally near identical.