Help me please.. i can't recover my Ubuntu 18.04 because i can't find any file on folder lost+found..
Sorry to hear about the trouble you're having here. There's a bit of missing detail that may help for myself or others to offer the best advice. You said that it can't boot, and then next that you're looking in the "lost+found" folder and not finding files that you need. Can you cover a bit more detail about the steps that you've gone through, the desired end result, and how the current situation differs from your expectation?
I know that's a lot to ask, but basically what I'm trying to accomplish is to mentally put myself in your shoes and see through your eyes. If I can understand the scenario better, I might have some advice to offer.
do i need a domain name to enable a droplet?
Why am I unable to access my website via the IP addess of droplet?
Can I have my own subnet?