Key phrase does not come on the 1st page of google

I am the webmaster of Initially, the keyword "erp for the manufacturing industry" was on the 1st page of Google for the landing page, but it is now on the 2nd page of Google. help me please to bring this keyword on the 1st page of google. I've tried page and page techniques but nothing works. Please help me in this regard.

Enjoy your comments.

thank you,
Sunil Nair