Link button not working in toolbar

Hello
when I started working on a page in my site, the link button is not allowing me to create a hyperlink to an external website. I can click the button, but it doesn’t do anything.
I also tried edited an existing link and it will not allow me to make any edits either.

I searched the forum and found many other have had this problem but they were all closed posts and were 2+ years old or older.

I did try deactivating all of my plugins but I still could not create a link.
I did not try using an old theme as suggested in another post, simply because I think I have a custom theme and did not want to mess anything up. I am not very computer savvy when it comes to wordpress and had someone else design my site, so I hope I am explaining this correctly :/
Any help will need to be written out step by step for me….even where to initially open or start! lol
Thanks in advance 😉