downgrade from php 5.5 to 5.3

[OsaMasw]

hello guys, good morning
one of our servers recently upgraded to Ubuntu 14.04 so for this PHP upgraded to 5.5.9
all scripts on this server stopped working because they use a functions not supported by newer version of PHP,
I need to downgrade PHP to 5.3 so I can make all scripts work again.
I dont care for security resons for updating PHP, so its ok to back to older version of PHP.
I used this tutorial but still my php 5.5

sudo apt-get purge php5
wget -O php5_3.tar.gz http://us1.php.net/get/php-5.3.28.tar.gz/from/this/mirror
tar -xzcf php5_3.tar.gz
cd php5_3
./configure
sudo make
sudo make install

But in ssh when using php -v
its shows like this

How about updating the few scripts that don't work? There can't be that many surely? Which functions are affected?

[OsaMasw]

as for error.log its show me a whole file with all functions like mysql_connect , mysqli_connect
I really dont know which function is not working.

Neither of those should cause a problem - even mysql_connect, but the migration (5.4->5.5) file states:

The original MySQL extension is now deprecated, and will generate E_DEPRECATED errors when connecting to a database. Instead, use the MySQLi or PDO_MySQL extensions.

Is your error log collecting ALL errors or just fatal ones? If all, then I imagine that the vast majority of them you can ignore (NOTICES and WARNINGS).