You can Run and print an audit of hardware and software including installed Product Keys using Belarc Advisor.
This audit assures you won't lose any paid software keys like Office.
Write down the Product Key from COA sticker located on back or side of PC tower, bottom or under battery of notebook.
Make sure you get the characters correct as this is a main cause of activation failure.
Note that the Windows 7 Product Key found by Belarc or another key finder will be an SLP batch key used at factory, if it has not yet been activated from COA sticker Key used for a Clean Reinstall. Methods for backing up Factory SLP Activation if the COA Product Key is not readable are not supported here but can be found on the web.
For unbootable Windows, you can read the installed Product Key and any Office key you don't have backed up using Produ Key - Recover lost product key (CD-Key) of Windows/MS-Office/SQL Server If you have a Recovery partition it may not run after clean reinstall.
If you have a retail copy of Windows 7, then you could try to download an ISO directly from Microsoft at the link below.
The link is reported to only work in Internet Explorer.
Favorite pre-installed apps may be found on the Downloads webpage for your model computer or manufacturer-provided Apps Disk. Some pre-installed apps may not be available for clean reinstall - more about this for your brand PC in the Special Notes at end.
You can download clean, safe copies of your licensed Office version to burn to disk (.iso) or run from Microsoft which can be activated with the Product Key you originally bought with it or audited using Belarc from Step 2 above.
You may want to make your Recovery Disks so you have a path back to factory condition, following the steps given in your PC's setup literature or in the Manual located on the Support Downloads webpage for your model computer.
As an alternative to Recovery Disks you can save a Windows 7 Backup Image or more flexible Macrium Image of the entire HD.
The exact make/model will be listed in your Device Manager under Network Adapters.