If you don't know too much about managing or troubleshooting your website it is always helpful to have some easy to use tools at your disposal. A website can be compromised in many different ways and search engines tend to be able to spot this and will warn users. You may have seen warnings on Google or Bing suggesting that you stay clear of some of the sites that appear in search results. If this happens to you it is going to have a dramatic effect on visitor numbers - and not in a nice way.
A Quick Diagnosis
You can get a free malware scan for your website by going to Securi's site check. You simply add your URL and press enter. The results are returned quite quickly and will give you an assessment of your site and its standing with various search engines. If you do have problems Securi will offer to fix them - at a cost. I have no affiliation with the company but do think this is a great tool to help diagnose a compromised site.
If You Do Have Problems
This is just a quick post to draw your attention to the Securi tool. I don't intend to provide details about what to do if you do have problems However I work in WordPress and have had to deal with hacked sites. It can be quite a tedious process and my advice would be to have a look at what Google has to say about the subject. If your site is clean you're good to go. However if you don't have it I suggest you install security software as a matter of urgency. For WordPress both Shield and WordFence have good reputations and offer free versions of their plugins.