I've an Apache server running which hosts a php web application. Also, its provides provisions for installing personal files of size around 900MB from this. However, while testing the applying I discovered that it is difficult to pause the downloads and resume them afterwards.

Could someone assist me to? Could it be an apache property I have to change?

Should you serve your files with php then you definitely should implement Range header processing inside your script. You are able to recieve current range value from $_SERVER['HTTP_RANGE']. It consists of the offset in bytes from begin of file.

ps: as usually pointed out - just about everything has already been clarified here -) http://stackoverflow.com/questions/157318/resumable-downloads-when-using-php-to-send-the-file/157447#157447