Unable to enter passcode on iPhone SE

The device passcode on an iPhone determines the type of input field you see when unlocking the device or making security changes. If you originally set an alphanumeric passcode (a combination of letters and numbers), the iPhone will show a text field when asking for the passcode. If you setup a numeric passcode, the iPhone will either show a 6-digit input field (for a standard 6-digit passcode) or a 4-digit input field if you chose the shorter option.

If your iPhone is only showing a 6-digit passcode field, but you expected an alphanumeric passcode field, there are a few possible reasons:

1. The passcode was changed:
   1. Someone who had temporary access to your device may have changed your passcode to a 6-digit numeric one.
   2. This could happen if they had access to your device’s settings and knew your old passcode.
2. You might be mistaken about the type of passcode: You may have set a 6-digit numeric passcode and misremembered using an alphanumeric one.
3. Reset or security changes: If your device was restored or reset and a new passcode was created during setup, this could explain the difference.

If you truly believe the passcode should be alphanumeric and it’s only allowing 6 digits, and you can’t recall changing it, you may need to take steps to recover access. The process is given below...

Your data is not lost if you have a backup either on iCloud or iTunes.

If you see an iPhone or iPad unavailable message or a "Security Lockout" screen

If you forgot your passcode, you can use your Apple ID and password to erase and reset your device without a computer.

Learn what to do if you see "[Device] unavailable" or "Security Lockout" on your iPhone or iPad.)

iPhone is disabled.

Following this process is the only way out if your iPhone is disabled. The steps given in this link will help you reset the passcode -> If you forgot the passcode for your iPhone, iPad, or iPod touch, or your ...

Regarding your data…

1. If you have an iCloud or iTunes latest backup, then there is nothing to worry about. If not read more...
2. You have synced your data to iCloud, then what you will get back is what you have synced to iCloud and uploaded to iCloud Drive; the information that is synced and stored in iCloud are, Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive. (*-If you have turned on iCloud Photos, your content is automatically stored in iCloud.)
3. You have imported your Photos and videos to Mac/PC then they are safely residing there on Mac/PC
4. You have uploaded some of it to Cloud Drives using the Files app (iCloud Drive, Google Drive, OneDrive, DropBox, Flickr, box, AmazonDrive, Adobe Creative Cloud, etc). The data remains there.
5. If you have not backed up or do not have the latest backup, nor imported nor you have synced or uploaded your data to cloud drives prior to the situation that you are in, then I am sorry, all your data is lost.