Option to boot into windows has gone after Yosemite 10.10.3 update

So after updating to Yosemite 10.10.3, the Windoes drive is no longer visible. Not visible in finder, not visible in startup disk but only shows as disk0s4 in diskutility. I've seen other guides similar, but i got lost and messed up a bunch, being inexperienced with OS X. Any help will be appreciated.