Hi welcome to TSG.
What those two have in common are the USB connections and the TWAIN files.
Look at the USB first. Do you have anything else plugged into the computer with the same type of plug? If you do, try a device that is working in one of the plugs for the scanner or card reader.
If you dont have another USB device to try in the plugs look in device manager. Right click My Computer>Properties>Device Manager. Go down to Universal Serial bus controllers and see if there are any yellow exclamation marks or red Xs beside it. Double click on it. Your card reader should probably be listed along with the universal host controller and root hub. If you have at least the last two items without any marks your USB is likely working. If there are any warning marks dont go any further and get back with what you see.
You might also go Start>Settings>Control Panel>Scanners and Cameras to make sure your scanner is listed there. If your card reader wasnt listed in device manager it could be there as well.
If the TWAIN drivers get corrupted devices dependent on twain drivers will have problems. The problem is that since various things can share the twain files they dont uninstall when you uninstall the software, and they dont get overwritten with good twain files with an install. What you have to do is uninstall the Epson software, remove the twain files and reinstall the Epson software. That is your best bet for getting back up and running.
Start>Settings>Control Panel>Add/Remove Programs. Find the Epson scanner software and highlight it. Then select Add/Remove and it will walk you through uninstalling it.
These are instructions for removing the TWAIN and TWUNK files from Mustek. Make sure you remove all of the TWAIN and TWUNK files in the Windows folder but do not remove any that are not in the Windows folder:
Windows 95/98/Me Instructions
1. Click on Start and select Find. Choose Files or Folders from the fly-out menu.
2. In the Find dialogue box type twain.
3. Make sure the Look In window has the C:\ drive selected and that the Include All Subfolders box is checked.
4. Click Find Now.
5. The lower part of the Find window will display the search results. Click on the Edit menu and choose Select All. (NOTE: Other programs, like Adobe PhotoShop have TWAIN files that will be found during the search. When all the files are highlighted, hold the CTRL key and click any TWAIN files located in other program directories, like Adobe PhotoShop, this will remove them from the highlighted selection. Only the TWAIN files located in the Windows directories should be removed.)
6. With all of the TWAIN files selected, click on File and select Delete.
7. Answer Yes and Yes to All to confirm the file deletion and send them to the Recycle Bin.
8. Once all the files are deleted, click the Find dialog box again and replace twain with twunk.
9. Click Find Now again.
10. As before, click on Edit and Select All then File and Delete.
11. Answer Yes and Yes to All to confirm the file deletion and send them to the Recycle Bin.
12. The TWAIN and twunk files are now removed and you can install the new driver
If you install the Epson software it will add the proper twain and twunk files.