In php.ini, this is the one:

upload_max_filesize

However, change only this line won’t help you to restore big db, so you have to setup some other factors as well
Try these different settings in C:\wamp\bin\apache\apache2.2.6\bin\php.ini
Find:
post_max_size = 8M
upload_max_filesize = 2M
max_execution_time = 30
max_input_time = 60
memory_limit = 8M

Change to:

post_max_size = 20M
upload_max_filesize = 20M
max_execution_time = 1000
max_input_time = 1000
memory_limit = 64M

And add this to C:\wamp\bin\mysql\mysql5.0.45\my.ini:
max_allowed_packet = 20M

Then restart wamp
Have fun