I posted this a while back, but the info is helpful also to those who are less technically knowledgeable. If you want to upgrade your wallet, just download the new one and use it. Simple as that. However, it is ALWAYS good to make a backup of your wallet.dat file and store it on a separate hard drive, flash drive, email works, but preferably somewhere safe and secure. Here are instructions that will help you access the file to backup and also redownload the blockchain if you wish.
For those who are still having issues, all you need to do is redownload the blockchain by doing the following 3 steps:
* Specific instructions are for Windows users, but these are the basic steps for everyone
1. Make a backup copy of your Tekcoin wallet.dat file in your Tekcoin folder (located at: C:\Users\[your admin user name]\AppData\Roaming). You should always have atleast one recent backup anyway. If not, do it now and store it in a separate folder or drive.
* AppData folder is hidden by default. In this case; open "Folder and Search Options" in the Organize tab (in folder view), then select the "view" tab and select "show hidden folders, files, and drives" under "show hidden files and folders". You will no be able to see and access the AppData folder.
2. Delete everything in your Tekcoin folder. This will erase the blockchain data and allow the Tekcoin wallet to download a new blockchain upon your next startup of the Tekcoin wallet. You should also download the new wallet at this time from tekcoin.org if you have not yet done so.
* Here is a direct link to the download page:
http://tekcoin.org/?page_id=263. To significantly speed up the download (syncing your wallet), download the bootstrap and put the unzipped files directly into your tekcoin wallet before downloading the fresh blockchain.
* Here is a direct link to the bootstrap:
https://mega.nz/#!DoIS2SbR!mNd1rsrXTYP183QDuqP9vnfqBOn7HCfUrQpx2t0eKbA