Well, the above situations are actually common these days, and you can find many Facebook users complaining about it. But the disappearance of chat is not a facebook fault, rather it is mainly caused due to the following reasons -
1. Slow Internet Connection
2. Browser Cache
So we'll now check and cross check for the above two reasons and we'll get you your Facebook chat back.
Slow Internet Connection - Slow Internet causes the Chat window to load extremely slowly and sometimes the Chat window doesn't not load at all ! This condition happens often with dial up connection users.
To check if your chat has disappeared due to slow internet do the following -
1. Log in to Facebook using a different browser. For example - if you were using Chrome earlier use Firefox to Log in to facebook now.
2. Check if your facebook chat is showing in that browser.
-> If you don't find the facebook chat then be sure that your Internet connection is too slow and you need get a faster connection.
-> if you found the facebook chat then congrats! Your Internet connection is doing good and now we need to get to the Browser Cache.Browser Cache - This problem occurs mostly (in fact wholly) in Google Chrome. Too much of cache and cookies stored by Chrome become the hindrance between you and your facebook chat. So all you need to is to clear your browser's Cache and Cookies.
Here's how to do it -
1. Press CTRL+H in Chrome to open browser History.
2. Click on Clear all browsing data. (button located on top)
You will find the following pop-up window -
3. Select the past day (highlighted in orange) from the drop down options and check (or tick) only the three options shown in the above screenshot.
4. Now click Clear browsing data button. (highlighted in Green)
5. Close and Restart Chrome again and Log in to Facebook. You'll now find your Facebook Chat Sidebar.
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