If you did not empty the Trash, click on the Trash icon at the right side of the Dockand drag those files to a different location.
If you emptied the Trash, it is more difficult. Typically, when a file is erase, it is not really erased. The space the file occupied become unallocated, so that new data can be written over that space. If new data files have not yet been written over that space, the old data is still there and may be recoverable.
There are utilities specifically for data recovery. For example (I have not used)
Other more general utilities, such as TechTool Pro by Micromat, have a data recovery "module" as part of the package. I have this utility (and it's a good product), but I have never used it for doing data recovery.
You may be able to use such tools to recover erased data. If you intend to try, you should use the disk that held the erased data as little as possible, to reduce the likelihood that new data files will be written over the space used by the old data.