Windows 10: What do I do??

I have a dell 5567 Inspiron 15 with windows 10 and I play the sims 4 on it. I bought an external gaming ssd device in order to make my game run smoother. However me being impulsive, I decided to add windows to my external ssd and boot my laptop using the ssd. It worked perfectly fine however the game was still loading slow so I decided okay I’ll re boot my laptop in its original format. Absolutely no go. I literally sat for 7 hours trying to fix it. I did everything from boot sequence to choosing my own laptop drive when booting however i kept going into a loop to “choose an option” menu no ma

:)