I don't have encryption on my wallet. Do you mean I should paste "listaddressgroupings" in the window that opens through "Help>Debug Log>Console" in Bitcoin Core? Also "dumpprivkey MYADRESS" would give me my WIP?

Bitcoin Client Software and Version Number: Bitcoin Core and Electrum (the latest versions)
Operating System: Windows 7 Ultimate 64-bit
System Hardware Specs: 3.1 GHz Eight-core CPU with 16 GB RAM
Description of Problem: Question regarding the recovery of bitcoins

So, before 3 years I had a bitcoin wallet, that I managed with Bitcoin core. I still have a backed-up version of the wallet.dat file from then.
My question is can I do these steps to recover my wallet:
1) Download Bitcoin Core and in the AppData\Bitcoin\wallet.dat, a new wallet.dat file is created - I replace the newly-created wallet.dat file with my old backed-up one.
2) Since my Bitcoin Core won't be synced yet, I won't have any bitcoins visible, but I think I would be able to see my private key in the Bitcoin Core client.
3) I would download Electrum and in a new Electrum wallet, I believe there is the option of sweeping bitcoins from a private key.

Is that possible, or am I missing something or doing something wrong?
Thank you to all, have a wonderful day!

Are those services safe? Can you suggest one, please? Thank you so much in advance, you have been of great help!

Sorry, by secret, I assume you mean "private key" and the answer is yes, I think he has it.

Hello to all the forum users,
Excuse my for my incompetence, please let me ask you a question.
A colleague of mine, who is really busy, used a BitCoin Wallet 2-3 years ago in which he had 50-60 coins, which he mined. He has a backed-up wallet file from then, but the issue he says is that the synchronization with all the transactions and what not (this part is not really clear to me) would take his computer from 2-3 weeks, having it non-stop working. The question I am trying to ask here is, is there an alternate, faster way to get his bitcoins back?