Welcome Alex Viveash,
Since losing access to months of Copilot history is your primary concern, it is important to determine which account actually contains the data before making any account changes. I would not recommend deleting any Microsoft account at this stage.
A few questions first:
- When you access the "old" Copilot on your mobile browser, can you open Settings > Account and confirm the exact sign-in method shown there (Microsoft account, Google sign-in, or an email address)?
- Do the two Microsoft accounts both use the same Gmail address as the sign-in name, or does one have a different Microsoft alias associated with it?
- When you try to sign in on the PC, do you receive any specific error message when requesting the SMS code, or does the code simply never arrive?
In the meantime, please try these checks:
- Go to https://account.microsoft.com and attempt to sign in with the Gmail address that contains your Copilot history.
- If Microsoft recognizes the address but asks for a password you do not know, select "Forgot password" and check whether recovery options are offered.
- While still signed in to the working Copilot session on your mobile device, review any account details shown under your profile and make a note of them. This may help identify which account owns the Copilot history.
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