Hi MissMac
I guess you're on a Mac? - What version of InDesign and what's your OS?
Make sure you're on the latest version for your version of Indesign - go to Help>Updates and ensure you're fully updated.
How did you place the file?
There's a few reasons why you can't select it.
1. It's locked - go to Object>Unlock All on Spread
2. It's locked in the Layers panel - go to Window>Layers, click the "triangle" arrow beside the Layer to reveal the sub layers - see if any of the lock icons are showing
3. You're on the wrong tool - If you have the type tool (or other tool) selected you can't select an image - you need to select the Black Arrow tool
If none of these options happen to work it could be minor corruption from within your file. To remove minor corruptions from an InDesign file you can go to File>Export (it's File>Save As in later versions of InDesign) and choose IDML (Indesign Markup Language) - this saves a new file to your drive. You can then open that (it opens as Untitled) and then see if the issue persists. You will then have to save your file to your preferred location within your folders.
Hope this helps.