Hi,
This is very critical error in magento.
1. First you go admin
2. Select system => Click Export your xls file.
3. There you can edit the case sensitive file path and file names
4. And check your extensions (ex : .jpg). Some time this is have “.JPG” => This type not working properly so, you need to change this extensions.
5. And save your .csv file. Then import admin via.
6. Again Go to System tool =>Select Index Management => select all checkboxes and click “reindexed”.
now its working properly. that’s all ЁЯЩВ