My outlook malfunctioned several days ago and Windows told me the .ost file was inaccessible. I searched some websites to solve this problem and Kernel for OST to PST software came to me. I downloaded it and used it to recover the OST file and then convert it to PST format quickly. The software works very fast and is simple to use; even if the emails are permanently deleted, it can also recover them. The most important thing is its trial version is free to download, so you can have a try before buying.