You can extract a replacement DLL file from your Windows CD. It's in the D:\win98\WIN98_34.CAB file, assuming that D: is the drive letter of your CD ROM.
Browse to your C:\Windows\System folder, rename the current dll file on your hard drive from MSJET35.DLL to MSJET35.old then extract the new file from your Windows CD to the C:\Windows\System folder. To do this, right click on the MSJET35 file in your D:\win98\WIN98_34.CAB on your Windows CD and choose the option to extract it. A pop up box appears where you can navigate to the folders on your hard drive. Target the C:\Windows\System folder.
This should get you up and running.