Answer
If vaccination records are lost and the information cannot be restored, you can be vaccinated again in Uruguay. The information clearly states that if no records are available, a person can simply be vaccinated locally, free of charge.
This solves a practical problem for those who cannot obtain an old vaccination card or extract. Instead of trying to prove what cannot be documented, it is easier to follow the local vaccination schedule and receive a clear Uruguayan certificate.
If any information has survived, it is worth taking it along to avoid unnecessary repeat vaccinations. But the complete loss of documents does not leave you at a dead end: the healthcare system provides for repeat vaccination and subsequent recording of the data.