‘How should I approach him?’

How do I approach a guy I like without making a fool of myself? We work together and chat sometimes, but don’t really know each other well at all. I just want to give him an idea that I find him interesting and would like to go out with him but saying anything is risky because I have no idea how he might take it. He could be offended, or snub me, which would make things very difficult and awkward at work. I have tried to smile at him more and speak a little about my life, but I still know little about his personal life. There is no information on social media either so it’s all a mystery. What should I do about this without getting myself into an embarrassing situation?
You can be direct and tell him that you would like to get to know him better if he’s okay with that. If that is too direct, you can ask questions about his personal life and see how open he is to talking about it. he may be reticent, and he is allowed to be, but there is no harm in asking a colleague questions that aren’t offensive. If he chooses to deflect them, that is his prerogative, but it will also tell you that he isn’t interested in opening up to you. If that happens, you can assume there is no reciprocal interest or ask him out for a cup of coffee which is a normal thing to do. Any situation that has the potential to turn awkward can be avoided by keeping things civil and impersonal.

A girl I used to chat with online has changed almost overnight and I can’t make sense of what has happened. I don’t know what I did. Should I apologise?
Given that these interactions are online, you don’t have any information of what is occurring offline. It could have nothing to do with you. Give her time and space and ask if you did anything to offend her.