Google XML Sitemap Plugin Install Fail: Could not copy file. /public_html/wp-con

Hello guys,

I’ve had this site https://most-underrated-songs-ever.com for a while, and at some point, had to take it offline (bad mistake) since then I put it back up, and started creating content again, but it seems like it’s not indexed anymore (that by itself is very strange, my GA code still seems to work and feed me data, but … when I google the exact keywords of my own site, I don’t appear anywhere! Alexa data when I click on it is… completely blank??? Am I … in the dreaded sandbox?)

Anyway. Long story short, I thought I’d install the Google XML Sitemap Generator plug-in, to make sure that the site would be well indexed again. Has rave review, and seems like great for run-o-the-mill SEO anyway. And it Fails everytime. Here’s the error message:

Could not copy file. /public_html/wp-content/plugins/google-sitemap-generator/lang/sitemap-zh_CN.po

Today, I got lucky, I had a new one when I tried:
Destination folder already exists. /public_html/wp-content/plugins/google-sitemap-generator/

So, since I know little about this and have a “can-do” approach (ahah) I have changed the CHMODs to 777 in a variety of folders, which changed the error message, but still did not solve the issue… (Speaking of which are there any wee software to scan a bit your registry and advise which folders you maybe should put back to CHMOD that are less liberal than 777? Because I try and always put them back to their original permissions but by now, am pretty sure I must have let some slip through)

I have looked in all sorts of forums, and not found anything close to it. I know I’m a total noob, but am I a freak of wordpress-nature too? ??

Extra info: I’m using a template I just installed called Fresh life: https://www.theme-junkie.com/2010/06/01/new-theme-freshlife-a-clean-and-fresh-wordpress-theme/

Also: Plug-ins currently present: Akismet version 2.4.0 / Quick Adsense version 1.7 (which I don’t use) / Ultimate Google Analytics version 1.6.0

Sorry if this post sounds like a cross between “War and Peace” and “National Lampoon’s The WordPress user” but I am now completely out of ideas. Any, ANY help would be most welcome. Thank you. Stephane.