An upgrade to the Lr-Classic app is sometimes known to create a new empty catalog that gives the appearance that your photos are "gone". (I experienced this when I kept my primary catalog on an external drive.)
So I suggest you start by using File explorer to search for all catalog files (Filetype suffix of .LRCAT) and [Double Click] on each until you find the catalog with your photos. This might be the remedy.
"Presets are gone" also suggests that you primary catalog may have stored presets within its parent folder, and a new empty catalog is now looking in the default location for Develop presets. (See Preference settings).
When you have recovered your primary catalog set the preferences to 'Always open this catalog'.