Major Problems Getting Images Loaded ... Hours Later ... help!?

Hi all, 

I have my photos on an external hard drive. Recently we disconnected that drive to run it through a check to be sure the drive was still okay because the other external drive I have connected had issues and had to be replaced. When we hooked it back up to my iMac (using most current Ventura) and opened up LR the images weren't there and VERY slowly are appearing. It is taking eons. Is this normal? Is there something I did wrong when disconnected the hard drive? Is there any way to speed this up? I keep my images in folders by year, and I'm currently working on getting 2013 loaded. 2012 took hours and hours. 

Prior to disconnecting this never happened. Everything just appeared immediately. 

I'm not good with computers, as I'm sure you've figured out by now. But really, should this be taking days? What the heck am I doing — or did I DO — wrong?! 

OH ... my husband reminds me that I accidentally unplugged the photography files hard drive when I meant to unplug the other hard drive, so it was improperly disconnected from my iMac. Could that mess things up this much? 

Thanks for any help.