A site can crash on my occasions due to various reasons. A hacker might barge into your file or your entire database can get destroyed or even a severe hard disk failure can occur. Therefore if a web host keeps some sort of backups on regular basis, then you can pretty much save yourself on such horrifying occasions.
Even if the host is able to restore some of your data, I say it can save you a whole lot. Just make sure to check if your web host provides full or some backups on regular or occasional basis. Site backups can sometimes be done via control panel and you can ask your host about it.
There may be options for you to restore your data yourself; you can check on that as well. Creating websites is not big a deal. Getting a good website host can help you avoid a lot of problems and maintain it too.