As others have mentioned in the comments, we don't know where you are located, and that impacts answers to this question. However, I recently did some research on trademarks vs. copyrights in the US, and I think some of the information I encountered might be useful to answering your question.
Here is some useful language from the United States Trademark and Patent Office:
A copyright protects original works of authorship including literary, dramatic, musical, and artistic works, such as poetry, novels, movies, songs, computer software, and architecture. The duration of copyright protection depends on several factors. For works created by an individual, protection lasts for the life of the author, plus 70 years. For works created anonymously, pseudonymously, and for hire, protection lasts 95 years from the date of publication or 120 years from the date of creation, whichever is shorter.
As they make clear elsewhere on the site, copyright is used to protect artistic/creative items--including font design, graphic elements, the shape of Mickey Mouse's head, etc.
A trademark is a word, phrase, symbol, and/or design that identifies and distinguishes the source of the goods of one party from those of others. A service mark is a word, phrase, symbol, and/or design that identifies and distinguishes the source of a service rather than goods. Some examples include: brand names, slogans, and logos. The term "trademark" is often used in a general sense to refer to both trademarks and service marks.
Knowing how protective Disney is with its intellectual property, I would venture to guess that Mickey Mouse's head is actually trademarked, not just copyrighted. But regardless, I would think that if you reuse an image protected under either a trademark or a copyright in such a way that it remains identifiable as that image, you are skirting very close to illegal usage, and unless you have a lawyer on standby, I would avoid that.
Hopefully, this can also provide you with an answer to your question about fonts. As is pretty clear from the definitions, words cannot be copyrighted, but the design of that word written in a particular typeface CAN be copyrighted. A word can be trademarked as part of a logo, but that doesn't necessarily mean that the word cannot be used elsewhere, it just means that the owner of the trademark has protected that word from usage in situations that are similar to the trademarked usage. (This part is a little more complex, and I am not sure I am doing it justice with this definition).
I know about using/purchasing stock and all that, I have accounts on all the stock sites, but I created a design, which resulted in some issues.The design had some copyrighted material
You may already be aware of this, but images on a stock site are usually divided into those that are available for "editorial" usage and those available for "artistic/creative" usage (the term used for "non-editorial" varies on different sites).
Here's the description of editorial use only images from iStock:
Unlike the majority of our collection, editorial photos don't have any model or property releases, which means they can't be used for commercial, promotional, advertorial or endorsement purposes. These images often include news, sports and entertainment images that portray real-world people, places, events and things and are intended to be used only in connection with events that are newsworthy or of general interest (for example, in a blog, textbook, newspaper or magazine article).
If you used an editorial image for your design, that could be the source of your copyright troubles. All of the paid stock sites I have ever used have a filter that allows you to search for only non-editorial images. I highly recommend turning that filter on immediately; I cannot tell you how many times I have forgotten, and found the perfect image, only to discover I can't use it. :-(