No idea - your question gives us nothing to go on.
When you say "sorting" your photos, what do you mean? Putting them in some specific sequence, or "sorting out" as in the British vernacular sense of "getting generally organised and fettled"?
When you say photos "disappear", what do you mean? Are they being deleted from your hard drive? Or is Lightroom ceasing to find/reference them?
When you say that more than half your keywords are "missing", what do you mean? Missing from the Lightroom database? Missing from exported images' IPTC data? Missing from presets?
And so on.
Over to you...
I started using Lightroom about a month ago. I imported all of my photos into Lightroom, and assume that they all show up in the Library "All Photographs" tab. In this tab, with no filters on, I have lost photos that were once imported. That is issue 1. Using the locate original file, or find file, no file is found. Fortunately, I have a back up on an external hard drive, where these photos still exist.
Issue 2. Keywords....I spent a couple hours on an afternoon simply adding keywords to photos I wanted to be able to find quickly in the thousands of photos in my library. I had around 100 keywords. I now only have about a dozen.