If the attachments in your LiveAgent are damaged after you download them to your computer, it is most probably because the collation of database is set to incorrect character set (most often it is 'latin1_swedish_ci'). You can check this value in your database administration tool e.g. PhpMyAdmin in view where you see list of tables in the right panel and in the very last line you can see the collation of the database:
Collation of database tables is set during installation by our installation script, but we have no control over the collation of the whole database which you created before the installation.
The database collation can be fixed by running this simple SQL command on your database:
ALTER DATABASE name_of_your_database CHARACTER SET utf8 COLLATE utf8_general_ci;
If only one table has the incorrect collation, you can try this command:
ALTER TABLE <table_name> CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_ci;
Unfortunately the broken files can not be fixed. The binary data was broken in the incorrect conversion and can not be restored.
See also Errors caused by UTF8 emoji characters why some columns must use utf8mb4_general_ci collation.