I have a grid covering some area and roads shapefile on the map. Now I want to make a screenshot of each grid square and save it as a picture. How I can do that using qgis? I have searched for plugins but with no success. Also I have tried to use print composer but I can't do the right thing for each square.
Use the Atlas Generation feature.
Here is a good tutorial: http://www.qgistutorials.com/en/docs/automating_map_creation.html