I would think that you would have to uninstall Vegas on your E: drive, then install it on your C: drive with the installation file you have when you bought Vegas. If you don't know where that's at, log into your Magix account and it will be there.
Seeing your latest screenshot I should not exactly know how My advice is to ask a computer Pro
i fix the issue so here is what i did
1. i uninstalled Vegas From D Drive then restart the pc 2. i want in to my download folder and fin the exe installer pack
3. i just install vegas 21 on C Drive
veg project still worked even through the icon is gone ,sfk . veg files
so i after i reinstalled Vegas 21 i think the software fixed itself cause i was able to rendering
V
with no System Memory Low warning or etc like that so all rendering projects go to the D Drive when complete since D And E Drives are my 10 TB EHD which has more space room on it pleas break in half (kind of)