WooCommerce disappeared…but says I still have it

I’m working on a site that I set up to use WooCommerce for both affiliate products as well as original products, but out of nowhere, it’s not showing WooCommerce anywhere in the administrative side of the site anymore. I thought it was strange since I didn’t delete it. I just thought I’d simply reinstall it, but I get this:

“Downloading install package from https://downloads.wordpress.org/plugin/woocommerce.2.3.8.zip…
Unpacking the package…
Installing the plugin…
Destination folder already exists. /home/content/27/11452527/html/wp-content/plugins/woocommerce/
Plugin install failed.”

I’ve found this topic in a couple different forums on various sites, but the answers don’t help me because they’re above my head. They’re saying to delete the woocommerce folder somewhere and reupload the theme via FTP. I downloaded FileZilla but I’ve never used FTP to do anything. Someone sent the link to Filezilla’s help file, but even THAT is Greek to me. I don’t even know how to connect FileZilla to the site because it’s a site for a client – I don’t know ports and usernames and passwords and what not. I tried to connect the site to the FTP, but it says it can’t connect to the server. I just designed the site – my client set up the domain, etc.

Is there no way around this but to manually reupload the theme through an FTP?

I’m so frustrated and spending way more time on this silly little problem than I should be. I absolutely love the theme and recommend it to many people to download, but they all need the WooCommerce plugin to work because they sell stuff.

Thank you for any help you can give me.