This is related to fonts, but there is not much you can do. When the PDF file was generated, the application that generated it did not provide a table that maps the "drawings of characters" (or glyphs) back to the the character(s) they represent. One potential workaround is to export the document as image files, and then import these images back into Acrobat, and then as a final step run OCR on this newly created file. You should now get better results as before.
I tried to do as you said. But Adobe can not recognize the text.
I have done: PDF - Image - PDF - Text Recognition - In This File - Primary OCR Language (Ukrainian) - Ok.
That's why I called it a "potential workaround" - in your case it did not work. Did you use a relatively high resolution for the image export (e.g. 600 dpi)?
Your only option (using just Acrobat) is to complain to the author of the PDF file and request a copy that is created with a better PDF generator. If you are open to using other software, you can try a dedicated OCR application (I keep Abbyy FineReader around for more challenging OCR jobs), to see if that would recognize the text in your images.
I used a relatively higt resolution for the image (600 dpi) and nothing And I tried another file, Adobe Reader recognized the text.
A lot of thanks for your help!