Based on my research, it does not appear that you are able to derive any additional of you private keys from only a single private key associated with you seed. You will need at the very least, the xpub key plus a single private key in order to calculate your other electrum private keys (at this point you can essentially "guess" the position of the private key in order to correctly calculate the other private keys fairly easily).
If you had accessed a block explorer while looking at your xpub key (eg you went to blockchain.info/xpub/xpub661MyMwA...) then you can look at you browsing history to find your xpub key (assuming your history has not been deleted).
I am not familiar with the directly that electrum keeps your wallet files by default, however if your wallet file was stored in the Documents, Music, Pictures, Videos, Desktop and OneDrive folders then it appears that Windows will automatically backup your files when changes are made to them. It appears this feature needs to be turned "on" and it is unclear if the feature is "on" by default. Please see
this page for more information on how to recover your files this way.
If windows has not automatically backed up you wallet file, then you are going to want to use some kind of data recovery software to try to recover your wallet file. I do not use windows, and as a result I would not be able to properly vet any specific software for me to recommend that you use. Doing a quick google search, I was able to find
this website that appears to be selling data recovery software as well as
this site that appears to compare various data recovery software programs.
It is important to note that if you download anything from a developer that you do not proactively trust then it is possible that you may be downloading malware, or something else that may otherwise damage your computer. You will need to do your own due dilligance to decide if any program found on either of the above links are safe to use. I do not have any reason to believe that any program in the above links contain anything malicious, however as mentioned above, I have not been able to vet any of the programs.
The longer you use your computer, the greater the chances that your wallet will end up being deleted/overwritten. If you have a lot of free space on your hard drive, then the chances of your data being overwritten would somewhat decrease, however you should certainly attempt to recover your files as soon as possible. If you can then you should download any software that you are going to download, and install any software that you are going to install on a hard drive that is separate from the hard drive that contains(ed) the wallet file that has gone missing.
If it turns out that you are unable to recover your wallet, then I hope this is not a lot of money for you, and hopefully this will serve as a lesson to have multiple backups of your wallet available
before you entrust your wallet with any BTC