We can try methods that don't require you to use a flash drive. However, these methods won't be a clean install so I don't know if they will fix everything for you but we can try. Let's start with the Windows Reset method. Below is a guide that I copy and pasted from another website.
Windows 10 comes with a feature called Reset This PC, using which you can either choose to keep your personal files or remove them and then reinstall Windows. Resetting is a good solution for a PC that isn't working well.
The merit of this solution is that Windows does not require any additional downloads nor installation media to initiate the setup.
Step 1: To do this, please go to Start > Settings > Update & security > Recovery.
Step 2: Click Get started under Reset this PCsection.
Step 3: Choose an option to continue. To reinstall Windows 10 without losing data, you should choose Keep my files.
Step 4: After the process has been prepared, a window will pop up saying that your apps will be removed. Click Next to go on.
Step 5: In Ready to reset this PC interface, click the Reset button to reinstall Windows 10 without CD or loss of personal files.
If this method fails you can try again using the remove everything option since you said there is nothing you need to backup.
Let me know if this method doesn't allow you to boot up Terraria still.