The text in the WordPress admin panel is not visible and all media files are deleted - why?

Question

WordPress

Before uploading the site to hosting, I worked with it locally. Upgraded the theme and installed plugins. At some point, photos began to be deleted from the site by themselves (all media files uploaded, for example, when creating articles). I can't connect to anything. I naively decided that this was a local problem, but after uploading to the hosting, things didn’t go better (xfmed.ru - if anyone is interested). There is no link to media files in the code where they should be (img src(unknown)). I create a new article, upload a photo to it. After a day or two, the photo disappears, but the text remains. The photo also disappears from the site folder.
This is half the trouble. Now again, for no reason at all, in the wordpress admin panel, the text is not visible due to the fact that it changes its color to the background color. With this, I have no idea what to do at all, because changing the theme in the settings does not help. Plus, I don’t know anymore, maybe I’m just clicking in the wrong place forever, as if at a certain moment new plugin settings are now flying off. In general, given that I am a beginner, I am absolutely confused and do not know what to do. It's a shame, given that I spent a lot of time developing ...