Hyper file(ndx) error

Hi,
We have application developed in WINDEV which uses hyper file database.
While importing files in the application we received following error:

Erreur d'acces a la base de donnees fichier PL_LIGNE_COLIS: Le fichier d'index.
PL_LIGNE_COLIS.ndx est corrompu. Vous devez reindexer votre fichier.

Does anybody know how to fix it?

Thanks in advance.