Opencart Expert to Fix Blank Sites

I am running 10 opencart stores from 8 separate installations. However, despite different software versions, different plugins and different templates, all have gone down overnight and I am left with just blank pages on the front end, even though cPanel and Admin panel are still functioning.

I need someone who can quickly help me to fix this and then who wants a couple of hours regular work each month to fix issues, update software, update security, add plugins and help me set up multistores.

Please can you give me an idea of timescale and cost, thanks.


EDITED 12/11

The sites are coming and going at the minute and I am now unable to see categories or add any products.

However it will be easier if you can quote an hourly rate as I need different sites giving priority and this will be ongoing work to keep everything updated and running smoothly.

Thanks