just in case this helps anyone, I was having this issue and I was doing everything I had done in previous projects/lessons while learning but the image still wouldn't show.

I had src="./Resources/Images/books.jpg" and compared to previous files with same format and was stumped. Turns out because I had moved the html files into a separate folder for multiple pages, the ./Resource path was no longer working. I had to but the full path in which worked.

src=

"C:\git_Repositories\Portfolio_Project\Resources/books.jpg"