What could be stopping me from merging columns in Excel ?

To give you an accurate answer without guessing, please share the following details:

1. What happens when you try to merge?
   Is the Merge & Center button greyed out, or do you get an error? If there’s an error, please copy the exact message.
2. Which cells or columns are selected?
   For example: A1:B1, entire columns A:B, etc. Are they adjacent?
3. Is the data formatted as an Excel Table?
   Click inside the data. If a Table Design tab appears, it’s a table—and tables don’t allow merged cells.
4. Is the worksheet protected?
   Go to the Review tab. Do you see Unprotect Sheet?
5. What file type is it?
   Is it .xlsx, .xls, .csv, etc.? Do you see [Compatibility Mode] in the title bar?
6. Is the workbook shared or co-authored?
   Look for [Shared] in the title bar, or other people editing at the same time.
7. What operating system and browser are you using?
   For example: Windows 11 + Chrome, macOS + Safari. Browser version is helpful if known.
8. Does the same problem happen in a brand-new blank workbook?
   Create one and try merging two cells.
9. If possible, a screenshot.

Please include the selected range, the Merge & Center button, and any error message.

Once you send these details, the cause can be pinpointed.

Without file or example is hard to reply.

Bye.