Wrong Level loading

Hi there ,
My Name is Rico , and I am new to this Forum ,therevore first , Hello to everybody .
I do Archviz vor many many Years now ,but only since about a half Year with UE4 .
I Love it .
My Issue i have :
I purchased a lot of stuff from the Marketplace ,mostly Materials and Models .
But one ore even more of the stuff there are corrupting my Project ?’
I believe it is a Blueprint in one of the Downloads ,still havent work out witch one .
Anyway .The Problem is wenn i add it to my Project from the Marketplace ,
my Level does not load anymore and it disapears from the View .All the stuff
in the content is still there . It looks like it is starting the Startermap now instead
of my Level .Anybody out there with the same problem ?
thanks for your time

I think the issue is not because of the Marketplace stuff, your level has corrupted.

If you go into the project folder, then into ‘Saved’, there might be a backup of your level in the ‘Backup’ folder. Also if you go to ‘Saved’ then the folder called ‘Logs’ you might be able to find the issue in one of the log files.

What version of UE are you using?

thanks for your time .
I am using 4.17.1 and i know i can get a back up file from the Saved folder . but if i copy
the latest Back up file in to my Content Folder and restart UE4 ,it still loads the Startermap with the ugly chair and table .
only after that i can load my back up File .
This would not be to bad ,but if i pack my Project for Windows 64 and want to play it , it only plays the Startermap
and that is very bad .hope you know what i mean .