A page that will not load is almost never a site that has gone down. In Bangladesh it is nearly always a block on that one address, and the fix usually takes under a minute.
What a block actually looks like
A blocked domain does not fail like a broken site. Look at which of these you are seeing — it tells you what kind of problem you have.
“This site can’t be reached” / DNS error — the most common. Your network refuses to translate the name into an address. The site is running; your connection will not look it up. A DNS change fixes this one.
The page hangs, then times out — the name resolved but the connection was dropped. Deeper than DNS; a different address is the quicker answer.
It loads on mobile data but not Wi-Fi (or the reverse) — that is conclusive. Two networks cannot both be down at once, so the site is fine and one operator is blocking.
A page loads, but says the site is unavailable — that is a real server error, not a block, and it is the one case where waiting is the right move.
What to try, in order
Open a different official address. Fastest fix there is, and no settings change. The current list is on the addresses page.
Switch your DNS to 1.1.1.1. Undoes most DNS-level blocking and is lighter than a VPN. Step-by-step for every device: changing your DNS.
Try the other network. Mobile data instead of Wi-Fi, or the reverse. This also tells you which operator is doing the blocking.
Check it is not just you before changing anything else — the four checks take about a minute.
Two things that will not help
Clearing your cache. It is the standard advice for everything and it does nothing for a block — the request never reaches the site.
Reinstalling your browser. Same reason. The problem is between your network and the domain, not inside the browser.
If a different official address opens straight away, nothing is wrong with your device and nothing needs fixing — bookmark the one that worked.