There should be a .dwl if the drawing is open, it is if it's there after a crash it may cause problems and by that be deleted before open TC again.
Maybe something gone wrong someplace in your file, so you could try to insert your file in to a New from scratch drawing.
Open e New from scratch, go to File/ Extract from, and Select the problemfile, check the Box in the Palette that opens so you get everything, save with a New name and see if that help's.
Or have e New from scratch open together with your problem drawing, go to Windows/ Tile and just drag it over, be aware you need to be in wireframe in both drawings, if you press ctrl after start dragging your selection, you will make a copy of the original.
V18, V19, V20, V21, 2015/ 16/ 17 Pro. Platinum
Deluxe V20, V21, 2015/ 16/ 17
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB