Photoshop unusable

Photoshop isn't usable. Last time I used it it was fine, it's v 19.1.1. Program opens fine, shows thumbnails of recent files, but trying to open one just flickers and goes back to the startup screen. This whether it's JPEG, PSD, PNG or TIFF. Trying to create a new file gives no response when the "Create" button is clicked. Nothing has changed this end... Files open fine in other programs. OS is Win10 Pro v1709 build 16299.125, processor is i5-4670, 16GB RAM on board, I've got a GeForce GTX 1050Ti with 12GB RAM in there too, and plenty of storage free.

Help!