I forgot the apple id because I created several months ago how do i reactivate it ?

Have you forgotten your Apple ID?, Check your Apple ID via your email box, see this Apple article: If you forgot your Apple ID

If you forgot your Apple ID email address or phone number - Apple Support                  

OR see -> Having trouble signing in?

https://iforgot.apple.com/password/verify/appleid

See -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

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Have you forgotten your Apple ID password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

B T W:

You are sign in here .  .  .  with your Apple ID & Password.

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password deleteappsyou use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

What happens when you use the same Apple ID & Password that you use to sign in here?

See the following Apple articles

Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support

Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)

This article tells you the various ways you can try to discover your forgotten Apple ID --> If you forgot your Apple ID email address or phone number - Apple Support Typically an Apple ID is an email address you have used. If you are currently using a mobile device that is logged into your account, go to Settings and tap your name at the top. Look in Keychain, and in a browser's security settings if you use it to automatically sign into Apple when using a browser.

This article outlines what to do If you forgot your Apple ID password --> If you forgot your Apple ID password - Apple Support

or go directly to this link --> http://iforgot.apple.com/

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

If you still need help:

Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." Click here --> Contact Apple for help with Apple ID account security - Apple Support