If you found that you can no longer open your OST file after a system crash, then the OST file has probably become corrupted or disenfranchised from your Outlook Profile. However, you can still access your emails by converting the OST file to MHTML format since you can open an MHTML file in any browser. A good option for this is Softaken OST to MHTML Converter. Softaken allows you to convert your entire OST mailbox, which contains all emails, documents, and formatting, to MHTML cleanly, without needing Outlook or Exchange. The process is simple; just load the ost file and select MHTML before starting the conversion. I used it once after a similar crash and it fetched the mail back into a readable document that I was able to open within Chrome.
Get More Info: https://www.softaken.com/ost-to-mhtml-converter

I encountered this exact scenario when my computer crashed and Outlook wouldn't open my OST file afterward. Every time I opened it, it brought up an error that said the file was damaged. I didn't want to lose any of my emails or attachments. After I struggled a bit, I found FixVare OST to MHTML Converter, which was a great help. It allowed me to convert my damaged OST file to MHTML format in a few easy clicks. After I did the conversion, I could open all my emails in a browser, like Chrome or Edge.
Everything was also preserved, including the formatting, attachments, and folder structure. If your OST file does not open after a crash, I would suggest converting to MHTML. I think it is the easiest way to recover and access your emails, even without Outlook.
Get More Info: https://www.fixvare.com/products/ost/mhtml/