Can't log into Microsoft account on PS4

In this case your best bet is contact Mojang support about this

They have a separate support team with different tools.

Hopefully they can look further on this matter for you:

https://help.minecraft.net/hc/en-us/requests/new

The issue is that I've never actually linked any accounts to my PlayStation so i don't know why its saying that i have a previous account connected.

Hi and thanks for reaching Microsoft Xbox gamer's community. My name is Josef.
I'm an Independent Advisor and a Microsoft Xbox user like you.

Hope you're doing great today despite this Aceed18

Sorry to hear that, as you're not able to find the correct Microsoft account linked to your PSN account, you may need to proceed with the account recovery form:
https://account.live.com/acsr

Because once you link an account is not possible to link a different one.
Is stated in the link below:
https://help.minecraft.net/hc/en-us/articles/36...

"WARNING Once a Microsoft account has been linked to a PlayStation:registered: account, neither the Microsoft account nor the PlayStation:tm: Network account can be associated with a different account. 

If you choose to unlink accounts, then purchases will be returned to the account which made the purchase. Even after unlinking, Microsoft and PlayStation:registered: accounts can only be re-linked to the original account."

If you're not able to find the correct account, you may need to use a different PSN account and link it to a new Microsoft account :c

Creating a Microsoft account with the old/previous email doesn't work.

If you're more than sure that one of your Microsoft accounts is the one connected to your PSN account. You can try contacting Mojang support and if possible send them proof of this.

Please note that from Microsoft side is not possible to view or unlink third party accounts

If you can sign into Microsoft account | Home perfectly fine, it means that perhaps your in gamer account in still linked to an old account that you no longer use. If you could sign into the website previously mentioned just fine, the best option would be to get in touch with the developer of the game for further assistance concerning the matter.

You can submit a request here => Submit a request – Home (minecraft.net)