I have a small amount and it is in Electrum.
That is when I was in trial and error phase. (Different wallets)
Then I forgot to keep the seed phrase in a physical paper.
I have kept it in a notepad somewhere in my computer (D: or E:) at work but cannot find it anymore once they fixed it due to viruses.
So it was left there and I think there is no way I could get it back. Besides, I don't want to put so much efforts into telling our computer technician to recover something.

The question is how much the amount. I dont remember it and the address was also in the notepad.

Unfortunately this has happened to me several times, the first instance of this happening was when a desktop wallet I was using stopped functioning and I realized that the development of the wallet had stopped as well, this had me very worried since I could not use the wallet at all to send my coins to another address, fortunately for me I remembered that at the beginning I made a paper backup of my seed words and after looking for them for a day I found them and I could generate my addresses in an electrum wallet.

There is nothing more embarrassing and hurtful when you got robbed  I got robbed on 2018, my bag with my laptop got away to me. That shit is freaking unexpected man, I'm just going home when these 2 guys suddenly ran up to me and pointed a sharp object to me, I didn't able to see if that was a knife or something but it was sharp, I'd better gave my bag than my life. I'm totally devastated at that point but luckily my phone is in my pocket, at least. I lost almost half of my access to my wallets, tokens and some other stuff that is important to crypto. I could probably bought a car with my savings on crypto, at the very least I got no losses from what I earned in 2017's blast.

One of the things we need to do when we have a cryptocurrency account or wallet is always making sure all of the transaction happens when we are making some transferring of funds. Most of the wallets today are now have a lot of different features to make sure that the user is reliable and verified. As a user of different accounts of cryptocurrency wallet, there are some features they made like two-way authentication; some of them are connected with the keygen that gives to you depends on the timer shown on your devices. Some of them are sending encrypted code to your devices that are connected with your phone number or email address. Also, it is better if we have a problem that is related to our account always make sure we will report to them because some of the admin are approachable and always give respect to them and takes a lot of time when they are updating them.

I was using yobit for exchange of bitcoin. At first everything was going fine and I was able to withdraw the bitcoin. But after a few weeks there was a problem and I was not able to withdraw my money. It is because there was some error. But the site soon repaired it and I could access my bitcoin.

Although I have not lost access to btc directly but recently I have lost access to my APL coin, I can't really say what am missing because I still have my private phrase to the wallet but for some waired reason the pass phrase suddenly don't work, this is same pass phrase I have used before,  now it no longer work and I can't transfer my coin out of wallet,
I should have sold those coin when I have access and buy a more wallet friendly coin.

My first bitcoins were on BTCGuild. I hoarded them before knowing much about Bitcoin and just let them sit in the account. Then I forgot all about Bitcoin and focused on university. Years later, BTC Guild now no longer exists and I have no idea how many Bitcoin I lost.

Not my Bitcoin but my Cousin and not Bitcoin but erc20 token,because he bought a token from another user and ask to send in his  wallet but he forgot where did he saved the private key of the said wallet and he did everything to find it because that time the token is pumping but suddenly?it was lost in the air.
that is what commonly happen from the past adopters when they have no much idea on which to use for hoarding and suddenly those company does not exist these days and they have no able access how to contact them.

What I have experieced is that,

The time when I decided to save enough bitcoin in my desktop wallet. Since I am confident that I am the only one who's using my PC, I only save my private key on the notepad. After the time goes by, my PC suddenly gets blue screen of death, yes, a sudden issue with my computer's hardware or what. I got worried since I don't have any back up information for my wallet, and unfortunately I cannot access my wallet anymore after I fixed my PC.