Fix my Joomla site

Hi, my website has a blank white page in Firefox. My website is Joomla. My web host upgraded PHP and I think Joomla and plugins needs an upgrade. It stopped showing the home page and now it is just white screen of death. My Joomla site has some pages and also a shopping cart. Just need PHP and Joomla expert to go in and make the updates to bring the site back up and running 100% functional again so my customers can order from my site again. Thank you for your bid, please bid if you are able to start, and my budget is 20.