If both ends of a ripped cassette tape are hanging out of the shell, the tape can be spliced without opening the shell. Follow these steps:
1. Run the backside of the tape over a rounded surface, such as a pen, to re-flatten it as best as possible.
2. Carefully align and reattach the strand ends against a backing of special Mylar splicing tape, then trim the excess off either side.
By following these steps, you can reconnect the ends of a ripped cassette tape without needing to open the shell. However, it is important to note that DIY repairs may not always provide the best results, and professional cassette tape restoration may be a better option for preserving the tape's quality.