You double-click the deck, the splash screen shows for a second, then the window disappears. No error dialog, no “PowerPoint has stopped working”, nothing in the title bar. Sometimes it happens with one file, sometimes with every file you open. The useful question is whether the program is closing itself or dying while it renders this deck. Those look identical and need different fixes. ...
A workbook that will not open usually fails in one of three ways: Excel reports the file format is wrong, it offers to repair and then repairs nothing, or it opens to a blank or partially empty sheet. Each has a different cause and a different first move. Try these in order. The order matters — step 6 is destructive, and steps 1 to 5 are not. ...
“Word experienced an error trying to open the file” is not one problem. It is a symptom with a short list of causes, and the cause decides which recovery method works. The good news: for .docx, the text almost always survives. The structure around it is what breaks. ...
If Word crashed, was force-quit, or the machine rebooted with a document open, the text is often still on disk. Word writes copies to three different places, and which one has your content depends on how far the crash was from your last save. Search them in this order. Do it before reopening Word, because opening a new document can overwrite the most useful folder. ...