My vault is suddenly empty across all platforms (Two different browsers (chrome, edge) web vault, Extension, Windows app, Android App)
Tried
Exported vault items, but every single entry is NULL
Please help somebody, my all important stuffs are gone from the vault…!!! 
@Thinking8519 Welcome to the forum!
Two things to try:
Log out completely (using a Log out button), and then log back in. For good measure, clear your browser cache and restart your browser (or Bitwarden app) before logging back in.
If you think that it is possible that your account was registered on bitwarden.eu instead of bitwarden.com, then select the .eu server on the login page (using the selector that is labeled “Logging in on” or just “Server”, below the username entry field).
I’ve logged out logged back in, cleared entire browser data, cache etc etc etc
No, I always used .com
Check your email for notices from [email protected] that begin with the text “Your Bitwarden account was just logged into from a new device” (Subject line will start with “New Device Logged In From …”). If you find any new device notices that you don’t recognize as your own login, then it is possible someone has compromised your account, and vandalized it. I consider this to be an unlikely explanation for your observations, but one that you should check for regardless.
Other than that, your best bet is probably to contact Bitwarden’s Customer Support.
No, I everyday check my email at morning, no unauthorized, suspicious login so far.
Yeah, just contacted Bitwarden support
To figure out where the issue is, you can check the browser console and network requests during login. Are there errors in the browser console? In the network requests, for the request to /sync, in the json, are the strings also null, similar to your export? (Do not post them here if they are not null, obviously).
Ok, from this it seems like the data is still there, it’s likely either the encryption key, or the encryption function that’s broken.
To test whether your web client has a en/decryption key you can paste the following into your browser console and hit enter:
bitwardenContainerService.cryptoService.getUserKey().then(e => console.log(e))
This will print your accounts encryption keys to the browser’s console.
DO NOT POST THE OUTPUT HERE, ONLY LOOK AT IT ON YOUR PC
the encKeyB64 and macKeyB64 should look similar to the screenshot below:
Ok, the the next question is whether the data is actually there, and if the crypto key matches the data. If you go to the network tab, then lock and unlock the vault, you should see a request to https://vault.bitwarden.com/api/sync?excludeDomains=true. It should look something like this:
Again, don’t post it, but are there strings of that form there, or is it null there aswell?
It’s getting complicated …let me try …hold on 
Maybe this will help:
sync item in the list on the left, and select it.Then scroll down and look for the “ciphers” section (not shown in my screenshot).
Yeah, I got it (Finally, my JavaScript, DOM skills are paying off)
now what i need to do ?
Sorry I had to create another account, bcz that account reached daily reply threshold limit. Again sorry…
Ok, seems there are still encrypted strings in that get synced. Either the decryption code is broken (though I wouldn’t know why the completely separate implementation on mobile would also be broken at the same moment), or the decryption key does not match the cipher strings.
For the export above, did you do password protected export or account protected export? There are other tools that can decrypt the vault, the issue is that they expect the account export format, not the sync json, which differ slightly.
I just did the normal .json export without any encryption
In case it’s an issue with the decryption code, one suggestion I could offer is to download an earlier version of the Portable Desktop App, run the downloaded .exe, and try to log in using that app.
