Need Macro to open and extract data from from multiple txt files

I need a macro to open all txt files in multiple folders and sub folders so that I can extract data before closing the files. My folder structure is "MainFolder/SubFolder1/SubSubfolder1". The txt files are within the SubSubFolders and I typically have 3 SubFolders and 24 SubSubFolders (3 days of data with a separate folder for each our of the day). I also need to only open the txt files as there are also csv files which I need to ignore. Any help would be appreciated. I effectively want to open each txt file (space delimited), extract several cells to a spreadsheet, close the file, and then move to the net file and repeat until all files have had their data extracted. Thanks.