can apple staff at Apple Store help me to unlock my iPhone without losing any data

I understand that you are referring to the Passcode that is used to unlock your iPhone to get to the Home Screen. Unfortunately, the answer to your question is a NO. You will need that passcode to save the data that is currently on the iPhone. If you have forgotten the passcode, then you will have to reset the passcode (as shown below) and that process will begin by erasing the data first.

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I understand that you are referring to the passcode that is used to get to the Home Screen of your iPhone. You will have to reset the passcode to your iPhone by following the instructions in this guide published by Apple 👉 Reset the Passcode of your iPhone (Without a Computer).  Note: All the data on your iPhone will be erased.

Hopefully, you have a backup created on 👉 iCloud and/or on a computer. If you do then, you can 👉 Restore your iPhone from the backup file once your passcode has been reset and the iPhone has been returned to factory settings by the procedure in the link above.

Axel F.

Your Lock Screen passcode? Was it within the last 72 hours? If so, see the following:

If you forgot a passcode that you changed within the last 72 hours, see the "If you recently changed passcodes, use your old passcode to temporarily sign in" section of: If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

Otherwise, there isn't any way you or Apple can unlock the phone without erasing the phone. But if you have a backup, you can restore the data. Also, any data synced with iCloud (such as iCloud Photos) won't be lost.

See the other sections of If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

If neither of the above is an option, you will need to use a computer. See: If you forgot your iPhone passcode, use your Mac or PC to reset it - Apple Support