A table arrives as a text file, but opening it puts each row into one spreadsheet cell. The contents may still be intact. The importing application might be interpreting the separator differently from the tool that exported the data.
Inspect a small example first
An invented row such as name;quantity;unit uses semicolons between fields. An import configured only for commas will not split it as intended. Look at a few rows in a text viewer or an import preview before changing the file.
Work with a copy when experimenting. Do not replace every punctuation mark across the document: a separator character may also occur inside a legitimate value, and decimal conventions introduce another reason to inspect carefully.
Check separators and quoted values together
Microsoft’s Text Import Wizard guidance explains both delimiters and text qualifiers, along with the preview used to check the resulting columns. A quoted value containing punctuation may belong in a single cell rather than two.
Controls differ between import tools and versions. Follow the documentation for the route you are using instead of assuming that double-clicking a file exposes every setting. Confirm the header row and at least one row containing a quoted or empty field.
Verify the data after the split
Correctly separated columns are only the first check. Look at identifiers with leading zeros, date-like strings, and values that should remain text. Compare them with the original file before saving your working spreadsheet.
Our article on file extensions and conversion explains why changing the filename alone does not fix interpretation. A short note recording the chosen separator and any column types makes the next import much easier to repeat.