It sounds like there could be a few potential issues causing your problem:

1. **Disconnected electrical connections:** Make sure all electrical connections were properly reconnected when you put the starter and alternator back in place. Check the battery terminals, ground connections, and all wiring related to the starter and alternator.

2. **Starter motor not engaging:** If the starter motor is not engaging when you turn the key, it could be a sign of a faulty starter solenoid or starter relay. Check these components to ensure they are functioning properly.

3. **Flywheel misalignment:** When you blocked the flywheel to replace the crankshaft bolt, there is a possibility that the flywheel is not aligned properly. This misalignment can prevent the starter from engaging with the flywheel teeth to crank the engine.

4. **Battery issues:** Ensure that your battery is fully charged and in good condition. A weak or dead battery can cause the symptoms you are experiencing.

5. **Fuse or relay:** Check the fuses and relays related to the starting system. A blown fuse or faulty relay can prevent the starter from receiving power.

Carefully go through these potential issues to identify the root cause of the problem with your vehicle not starting after the repairs you performed.