Why is Bitcoin lost password not recoverable?

[Patikno]

I think some of friends here have already provided the answer, and you can read it slowly, or with full attention. Additionally, as owners of our phrase or private key wallets, we should already be aware of the potential for Bitcoin loss, if we don't safeguard them properly. Therefore, it is crucial to perform a series of backups, which should be done offline, stored securely, and never stored online. We can store them on external storage, such as an SSD, but once again, never try to connect it to an unsecured device, and avoid direct online connections to the drive. We also need to realize that we don't know how long we will live, so we need to leave a legacy, but make sure they can't access it before we die.

By the way, I think you need to read the following thread which discusses a Bitcoin recovery tool : bitcointalk.org - The FinderOuter, a bitcoin recovery tool by @Coding Enthusiast

[Z390]

Listen attentively, what is the name of the Bitcoin wallet you used lately? It seems that you have found a Bitcoin wallet that let's you log into the wallet using email and password? I am happy you created this topic because you are about to make the same mistake that I did few years ago.
There is a difference between a custodial and non custodial wallet, any wallet that gives you access to your Bitcoin by just logging into your account they are custodial wallet, do not use them to store your Bitcoin.
All you need is a wallet that gives you total control via recovery seed or private key, don't use wallets that hides these two important backup and replace them with log in as if you want to log into a website account.

Examples are Bitgo, cobo wallet, freewallet, Coinbase, avoid them at all cost.
Go for unstoppable wallet, Electrum wallet, Blue wallet, Trezor, these are examples of Non-custodial Bitcoin wallets.

[DYING_S0UL]

...snip...

When I first joined this forum, I also had similar questions. Like why can't we recover lost Bitcoin or can anybody brute force my address and steal my Bitcoin?! Well, without going deep, I'll just quote the answer I got at that time. Btw, by password you meant seed phrase right?

Also, check out this video below and you'll understand why you can't recover it, in extend how secure Bitcoin is. The concept is the same in both cases, I guess.

https://www.youtube.com/watch?v=S9JGmA5_unY

Once lost, forever lost.

Another small question, why does BIP39 has only 2048 words? What's the reason? Is it related to any maths or equations?

Here's the small answer  

Because the entropy (plus checksum) where the mnemonic seed is based from is sorted per 11-bits, each of those 11-bit part corresponds to a word.
Then the reason for "2048" is because that is the limit that an 11-bit number can do, from 00000000000 (0 in decimal) to 11111111111 (2047 in decimal)

Let me illustrate this answer