please someone help me! I have an ED.SEILER upright wood piano with ivory keys, that's from 1911 (so it's 106 years old) and some of the black keys stopped working! It was working perfectly like a week ago! I'm in major panic! What do I do???
Did you do anything between the black keys working and them not working? Like moving the piano, or taking the front off to 'have a look' and maybe also have a fiddle? Or might someone else have? This can happen when the action has been taken out and not replaced properly.
Anyway, you won't do any great harm by removing the front panel and having a look. Is everything in place? Has anything fallen into the piano? Are some notes 'stuck'? But if there isn't an obvious simple solution, call a piano tuner/technician. Don't risk further damage by poking around beyond your capabilities.