Hi metoo, question marks instead of non-ASCII characters usually mean that the browser is not sure how to display Hebrew or Cyrillic and anything that is not the good old plain ASCII. Why that happened to you is to be determined, there are lots of possibilities. If you share the URL of your home page I can try and give a look. Meanwhile, do you remember editing the web page yourself (and if yes, how did you edit it)? Did you upgrade or change something else? Is the site on shared hosting or VPS or somewhere else? Sometimes the error is in the browser only: did you confirm that the site is displayed incorrectly also on other computers, or phone?
Please share more details and we'll do our best to help you get your site readable again.