After a bit goggling i got the simple procedure to build a Ubuntu repository.some people  reading this might think why should u construct this,the biggest advantages is to save the bandwidth and time .

simple steps to construct the Ubuntu package repository

packages are kept in the default directory /var/cache/apt/archives

step 1: Navigate to the location (/var/cache/apt/archives) and execute following command

# cd /var/cache/apt/archives
# dpkg-scanpackages . /dev/null | gzip -9c > /var/cache/apt/archives/Packages.gz

P in Packages.gz is uppercase be care ful while executing it
Result: This will create a Packages.gz (compressed file) in the same location ,if u want to examine the file just extract it and it return a txt file containing the packages information and all.
Thus ends step 1

step 2:creating a source url
remove all the entries and in source.lst and add the following entry in that
deb file:///var/cache/apt archives/

Execute the command

#apt-get update

to update the repository